Add missing 'const' on selftest data
diff --git a/library/sha1.c b/library/sha1.c
index 35e0625..fca6109 100644
--- a/library/sha1.c
+++ b/library/sha1.c
@@ -476,7 +476,7 @@
 /*
  * FIPS-180-1 test vectors
  */
-static unsigned char sha1_test_buf[3][57] =
+static const unsigned char sha1_test_buf[3][57] =
 {
     { "abc" },
     { "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq" },
@@ -501,7 +501,7 @@
 /*
  * RFC 2202 test vectors
  */
-static unsigned char sha1_hmac_test_key[7][26] =
+static const unsigned char sha1_hmac_test_key[7][26] =
 {
     { "\x0B\x0B\x0B\x0B\x0B\x0B\x0B\x0B\x0B\x0B\x0B\x0B\x0B\x0B\x0B\x0B"
       "\x0B\x0B\x0B\x0B" },
@@ -521,7 +521,7 @@
     20, 4, 20, 25, 20, 80, 80
 };
 
-static unsigned char sha1_hmac_test_buf[7][74] =
+static const unsigned char sha1_hmac_test_buf[7][74] =
 {
     { "Hi There" },
     { "what do ya want for nothing?" },