[test] Avoid using "static const" for test declarations

gcc will not warn about unused constant static variables.  An unused
test declaration is almost certainly a bug, so ensure that warnings
are generated.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/tests/aes_cbc_test.c

 	static const uint8_t name ## _iv [] = iv_array;			\
 	static const uint8_t name ## _plaintext [] = plaintext_array;	\
 	static const uint8_t name ## _ciphertext [] = ciphertext_array;	\
-	static const struct aes_cbc_test name = {			\
+	static struct aes_cbc_test name = {				\
 		.key = name ## _key,					\
 		.key_len = sizeof ( name ## _key ),			\
 		.iv = name ## _iv,					\

src/tests/hash_df_test.c

 #define HASH_DF_TEST( name, hash_algorithm, input_array, expected_array ) \
 	static const uint8_t name ## _input [] = input_array;		  \
 	static const uint8_t name ## _expected [] = expected_array;	  \
-	static const struct hash_df_test name = {			  \
+	static struct hash_df_test name = {				  \
 		.hash = &(hash_algorithm),				  \
 		.input = name ## _input,				  \
 		.input_len = sizeof ( name ## _input ),			  \

src/tests/hmac_drbg_test.c

 				    key, value )			\
 	static const uint8_t name ## _key [] = key;			\
 	static const uint8_t name ## _value [] = value;			\
-	static const struct hmac_drbg_test_instantiate name = {		\
+	static struct hmac_drbg_test_instantiate name = {		\
 		.hash = HMAC_DRBG_HASH ( hmac_drbg ),			\
 		.out_len = HMAC_DRBG_OUTLEN_BYTES ( hmac_drbg ),	\
 		.entropy = entropy_array,				\
 			       additional_array, key, value )		\
 	static const uint8_t name ## _key [] = key;			\
 	static const uint8_t name ## _value [] = value;			\
-	static const struct hmac_drbg_test_reseed name = {		\
+	static struct hmac_drbg_test_reseed name = {			\
 		.hash = HMAC_DRBG_HASH ( hmac_drbg ),			\
 		.out_len = HMAC_DRBG_OUTLEN_BYTES ( hmac_drbg ),	\
 		.entropy = entropy_array,				\
 	static const uint8_t name ## _key [] = key;			\
 	static const uint8_t name ## _value [] = value;			\
 	static const uint8_t name ## _data [] = data;			\
-	static const struct hmac_drbg_test_generate name = {		\
+	static struct hmac_drbg_test_generate name = {			\
 		.hash = HMAC_DRBG_HASH ( hmac_drbg ),			\
 		.out_len = HMAC_DRBG_OUTLEN_BYTES ( hmac_drbg ),	\
 		.additional = additional_array,				\
  */
 #define HMAC_DRBG_TEST_GENERATE_FAIL( name, hmac_drbg,			\
 				      additional_array, len )		\
-	static const struct hmac_drbg_test_generate_fail name = {	\
+	static struct hmac_drbg_test_generate_fail name = {		\
 		.hash = HMAC_DRBG_HASH ( hmac_drbg ),			\
 		.additional = additional_array,				\
 		.additional_len = sizeof ( additional_array ),		\