enable-ec_nistp_64_gcc_128: Fix function prototype warning [-Wstrict-prototypes]

Fix prototype warnings triggered by -Wstrict-prototypes when configuring
with `enable-ec_nistp_64_gcc_128`
Reviewed-by: NKurt Roeckx <kurt@roeckx.be>
Reviewed-by: NMatthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/6556)

crypto/ec/ecp_nistp224.c

@@ -1212,7 +1212,7 @@ static void batch_mul(felem x_out, felem y_out, felem z_out,
  * FUNCTIONS TO MANAGE PRECOMPUTATION
  */
 
-static NISTP224_PRE_COMP *nistp224_pre_comp_new()
+static NISTP224_PRE_COMP *nistp224_pre_comp_new(void)
 {
     NISTP224_PRE_COMP *ret = OPENSSL_zalloc(sizeof(*ret));
 

crypto/ec/ecp_nistp256.c

@@ -1832,7 +1832,7 @@ const EC_METHOD *EC_GFp_nistp256_method(void)
  * FUNCTIONS TO MANAGE PRECOMPUTATION
  */
 
-static NISTP256_PRE_COMP *nistp256_pre_comp_new()
+static NISTP256_PRE_COMP *nistp256_pre_comp_new(void)
 {
     NISTP256_PRE_COMP *ret = OPENSSL_zalloc(sizeof(*ret));
 

crypto/ec/ecp_nistp521.c

@@ -1671,7 +1671,7 @@ const EC_METHOD *EC_GFp_nistp521_method(void)
  * FUNCTIONS TO MANAGE PRECOMPUTATION
  */
 
-static NISTP521_PRE_COMP *nistp521_pre_comp_new()
+static NISTP521_PRE_COMP *nistp521_pre_comp_new(void)
 {
     NISTP521_PRE_COMP *ret = OPENSSL_zalloc(sizeof(*ret));
 

engines/e_padlock.c

@@ -199,10 +199,10 @@ struct padlock_cipher_data {
 };
 
 /* Interface to assembler module */
-unsigned int padlock_capability();
+unsigned int padlock_capability(void);
 void padlock_key_bswap(AES_KEY *key);
 void padlock_verify_context(struct padlock_cipher_data *ctx);
-void padlock_reload_key();
+void padlock_reload_key(void);
 void padlock_aes_block(void *out, const void *inp,
                        struct padlock_cipher_data *ctx);
 int padlock_ecb_encrypt(void *out, const void *inp,

test/ectest.c

@@ -1167,7 +1167,7 @@ static int internal_curve_test_method(int n)
  * implementations of several NIST curves with characteristic > 3.
  */
 struct nistp_test_params {
-    const EC_METHOD *(*meth) ();
+    const EC_METHOD *(*meth) (void);
     int degree;
     /*
      * Qx, Qy and D are taken from