Rename globals to avoid shadowing by various function arguments

It's easier and more telling to rename the globals used only for test,
rather than rename all the shadowing function arguments.
diff --git a/library/gcm.c b/library/gcm.c
index 675926a..8294019 100644
--- a/library/gcm.c
+++ b/library/gcm.c
@@ -560,7 +560,7 @@
 static const int key_index[MAX_TESTS] =
     { 0, 0, 1, 1, 1, 1 };
 
-static const unsigned char key[MAX_TESTS][32] =
+static const unsigned char key_test_data[MAX_TESTS][32] =
 {
     { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
@@ -572,13 +572,13 @@
       0x6d, 0x6a, 0x8f, 0x94, 0x67, 0x30, 0x83, 0x08 },
 };
 
-static const size_t iv_len[MAX_TESTS] =
+static const size_t iv_len_test_data[MAX_TESTS] =
     { 12, 12, 12, 12, 8, 60 };
 
 static const int iv_index[MAX_TESTS] =
     { 0, 0, 1, 1, 1, 2 };
 
-static const unsigned char iv[MAX_TESTS][64] =
+static const unsigned char iv_test_data[MAX_TESTS][64] =
 {
     { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
       0x00, 0x00, 0x00, 0x00 },
@@ -594,7 +594,7 @@
       0xa6, 0x37, 0xb3, 0x9b },
 };
 
-static const size_t add_len[MAX_TESTS] =
+static const size_t add_len_test_data[MAX_TESTS] =
     { 0, 0, 0, 20, 20, 20 };
 
 static const int add_index[MAX_TESTS] =
@@ -737,7 +737,7 @@
       0x44, 0xae, 0x7e, 0x3f },
 };
 
-static const unsigned char tag[MAX_TESTS * 3][16] =
+static const unsigned char tag_test_data[MAX_TESTS * 3][16] =
 {
     { 0x58, 0xe2, 0xfc, 0xce, 0xfa, 0x7e, 0x30, 0x61,
       0x36, 0x7f, 0x1d, 0x57, 0xa4, 0xe7, 0x45, 0x5a },
@@ -797,7 +797,7 @@
                 mbedtls_printf( "  AES-GCM-%3d #%d (%s): ",
                                 key_len, i, "enc" );
 
-            ret = mbedtls_gcm_setkey( &ctx, cipher, key[key_index[i]],
+            ret = mbedtls_gcm_setkey( &ctx, cipher, key_test_data[key_index[i]],
                                       key_len );
             /*
              * AES-192 is an optional feature that may be unavailable when
@@ -816,14 +816,14 @@
 
             ret = mbedtls_gcm_crypt_and_tag( &ctx, MBEDTLS_GCM_ENCRYPT,
                                         pt_len[i],
-                                        iv[iv_index[i]], iv_len[i],
-                                        additional[add_index[i]], add_len[i],
+                                        iv_test_data[iv_index[i]], iv_len_test_data[i],
+                                        additional[add_index[i]], add_len_test_data[i],
                                         pt[pt_index[i]], buf, 16, tag_buf );
             if( ret != 0 )
                 goto exit;
 
             if ( memcmp( buf, ct[j * 6 + i], pt_len[i] ) != 0 ||
-                 memcmp( tag_buf, tag[j * 6 + i], 16 ) != 0 )
+                 memcmp( tag_buf, tag_test_data[j * 6 + i], 16 ) != 0 )
             {
                 ret = 1;
                 goto exit;
@@ -840,22 +840,22 @@
                 mbedtls_printf( "  AES-GCM-%3d #%d (%s): ",
                                 key_len, i, "dec" );
 
-            ret = mbedtls_gcm_setkey( &ctx, cipher, key[key_index[i]],
+            ret = mbedtls_gcm_setkey( &ctx, cipher, key_test_data[key_index[i]],
                                       key_len );
             if( ret != 0 )
                 goto exit;
 
             ret = mbedtls_gcm_crypt_and_tag( &ctx, MBEDTLS_GCM_DECRYPT,
                                         pt_len[i],
-                                        iv[iv_index[i]], iv_len[i],
-                                        additional[add_index[i]], add_len[i],
+                                        iv_test_data[iv_index[i]], iv_len_test_data[i],
+                                        additional[add_index[i]], add_len_test_data[i],
                                         ct[j * 6 + i], buf, 16, tag_buf );
 
             if( ret != 0 )
                 goto exit;
 
             if( memcmp( buf, pt[pt_index[i]], pt_len[i] ) != 0 ||
-                memcmp( tag_buf, tag[j * 6 + i], 16 ) != 0 )
+                memcmp( tag_buf, tag_test_data[j * 6 + i], 16 ) != 0 )
             {
                 ret = 1;
                 goto exit;
@@ -872,14 +872,14 @@
                 mbedtls_printf( "  AES-GCM-%3d #%d split (%s): ",
                                 key_len, i, "enc" );
 
-            ret = mbedtls_gcm_setkey( &ctx, cipher, key[key_index[i]],
+            ret = mbedtls_gcm_setkey( &ctx, cipher, key_test_data[key_index[i]],
                                       key_len );
             if( ret != 0 )
                 goto exit;
 
             ret = mbedtls_gcm_starts( &ctx, MBEDTLS_GCM_ENCRYPT,
-                                      iv[iv_index[i]], iv_len[i],
-                                      additional[add_index[i]], add_len[i] );
+                                      iv_test_data[iv_index[i]], iv_len_test_data[i],
+                                      additional[add_index[i]], add_len_test_data[i] );
             if( ret != 0 )
                 goto exit;
 
@@ -907,7 +907,7 @@
                 goto exit;
 
             if( memcmp( buf, ct[j * 6 + i], pt_len[i] ) != 0 ||
-                memcmp( tag_buf, tag[j * 6 + i], 16 ) != 0 )
+                memcmp( tag_buf, tag_test_data[j * 6 + i], 16 ) != 0 )
             {
                 ret = 1;
                 goto exit;
@@ -924,14 +924,14 @@
                 mbedtls_printf( "  AES-GCM-%3d #%d split (%s): ",
                                 key_len, i, "dec" );
 
-            ret = mbedtls_gcm_setkey( &ctx, cipher, key[key_index[i]],
+            ret = mbedtls_gcm_setkey( &ctx, cipher, key_test_data[key_index[i]],
                                       key_len );
             if( ret != 0 )
                 goto exit;
 
             ret = mbedtls_gcm_starts( &ctx, MBEDTLS_GCM_DECRYPT,
-                              iv[iv_index[i]], iv_len[i],
-                              additional[add_index[i]], add_len[i] );
+                              iv_test_data[iv_index[i]], iv_len_test_data[i],
+                              additional[add_index[i]], add_len_test_data[i] );
             if( ret != 0 )
                 goto exit;
 
@@ -960,7 +960,7 @@
                 goto exit;
 
             if( memcmp( buf, pt[pt_index[i]], pt_len[i] ) != 0 ||
-                memcmp( tag_buf, tag[j * 6 + i], 16 ) != 0 )
+                memcmp( tag_buf, tag_test_data[j * 6 + i], 16 ) != 0 )
             {
                 ret = 1;
                 goto exit;