fix char* vs. const char* (tests related part)

src/misc/hkdf/hkdf_test.c

@@ -40,7 +40,7 @@ int hkdf_test(void)
 
     static const struct hkdf_test_case {
         int num;
-        char* Hash;
+        const char* Hash;
         unsigned char IKM[80];
         unsigned long IKM_l;
         unsigned char salt[80];

src/misc/pkcs5/pkcs_5_test.c

@@ -35,9 +35,9 @@ int pkcs_5_test (void)
  #else
 
     typedef struct {
-        char* P;
+        const char* P;
         unsigned long P_len;
-        char* S;
+        const char* S;
         unsigned long S_len;
         int c;
         unsigned long dkLen;