New MD API: rename functions from _ext to _ret

The _ext suffix suggests "new arguments", but the new functions have
the same arguments. Use _ret instead, to convey that the difference is
that the new functions return a value.
diff --git a/tests/suites/test_suite_mdx.function b/tests/suites/test_suite_mdx.function
index 387e7ee..648a9cc 100644
--- a/tests/suites/test_suite_mdx.function
+++ b/tests/suites/test_suite_mdx.function
@@ -19,7 +19,7 @@
 
     strncpy( (char *) src_str, text_src_string, sizeof(src_str) - 1 );
 
-    ret = mbedtls_md2_ext( src_str, strlen( (char *) src_str ), output );
+    ret = mbedtls_md2_ret( src_str, strlen( (char *) src_str ), output );
     TEST_ASSERT( ret == 0 ) ;
     hexify( hash_str, output, sizeof  output );
 
@@ -41,7 +41,7 @@
 
     strncpy( (char *) src_str, text_src_string, sizeof(src_str) - 1 );
 
-    ret = mbedtls_md4_ext( src_str, strlen( (char *) src_str ), output );
+    ret = mbedtls_md4_ret( src_str, strlen( (char *) src_str ), output );
     TEST_ASSERT( ret == 0 );
     hexify( hash_str, output, sizeof  output );
 
@@ -63,7 +63,7 @@
 
     strncpy( (char *) src_str, text_src_string, sizeof(src_str) - 1 );
 
-    ret = mbedtls_md5_ext( src_str, strlen( (char *) src_str ), output );
+    ret = mbedtls_md5_ret( src_str, strlen( (char *) src_str ), output );
     TEST_ASSERT( ret == 0 );
     hexify( hash_str, output, sizeof  output );
 
@@ -85,7 +85,7 @@
 
     strncpy( (char *) src_str, text_src_string, sizeof(src_str) - 1 );
 
-    ret = mbedtls_ripemd160_ext( src_str, strlen( (char *) src_str ), output );
+    ret = mbedtls_ripemd160_ret( src_str, strlen( (char *) src_str ), output );
     TEST_ASSERT( ret == 0 );
     hexify( hash_str, output, sizeof output );
 
diff --git a/tests/suites/test_suite_shax.function b/tests/suites/test_suite_shax.function
index b6f8f51..d704b38 100644
--- a/tests/suites/test_suite_shax.function
+++ b/tests/suites/test_suite_shax.function
@@ -18,7 +18,7 @@
 
     src_len = unhexify( src_str, hex_src_string );
 
-    TEST_ASSERT( mbedtls_sha1_ext( src_str, src_len, output ) == 0 );
+    TEST_ASSERT( mbedtls_sha1_ret( src_str, src_len, output ) == 0 );
     hexify( hash_str, output, 20 );
 
     TEST_ASSERT( strcmp( (char *) hash_str, hex_hash_string ) == 0 );
@@ -39,7 +39,7 @@
 
     src_len = unhexify( src_str, hex_src_string );
 
-    TEST_ASSERT( mbedtls_sha256_ext( src_str, src_len, output, 1 ) == 0 );
+    TEST_ASSERT( mbedtls_sha256_ret( src_str, src_len, output, 1 ) == 0 );
     hexify( hash_str, output, 28 );
 
     TEST_ASSERT( strcmp( (char *) hash_str, hex_hash_string ) == 0 );
@@ -60,7 +60,7 @@
 
     src_len = unhexify( src_str, hex_src_string );
 
-    TEST_ASSERT( mbedtls_sha256_ext( src_str, src_len, output, 0 ) == 0 );
+    TEST_ASSERT( mbedtls_sha256_ret( src_str, src_len, output, 0 ) == 0 );
     hexify( hash_str, output, 32 );
 
     TEST_ASSERT( strcmp( (char *) hash_str, hex_hash_string ) == 0 );
@@ -81,7 +81,7 @@
 
     src_len = unhexify( src_str, hex_src_string );
 
-    TEST_ASSERT( mbedtls_sha512_ext( src_str, src_len, output, 1 ) == 0 );
+    TEST_ASSERT( mbedtls_sha512_ret( src_str, src_len, output, 1 ) == 0 );
     hexify( hash_str, output, 48 );
 
     TEST_ASSERT( strcmp( (char *) hash_str, hex_hash_string ) == 0 );
@@ -102,7 +102,7 @@
 
     src_len = unhexify( src_str, hex_src_string );
 
-    TEST_ASSERT( mbedtls_sha512_ext( src_str, src_len, output, 0 ) == 0 );
+    TEST_ASSERT( mbedtls_sha512_ret( src_str, src_len, output, 0 ) == 0 );
     hexify( hash_str, output, 64 );
 
     TEST_ASSERT( strcmp( (char *) hash_str, hex_hash_string ) == 0 );