Fix Windows build failures caused by 310d4dd.

MSVC doesn't like |const size_t len| in a function definition where the
declaration was just |size_t len| without the |const|. Also, MSVC needs
declarations of parameterless functions to have a |void| parameter list.

Change-Id: I91e01a12aca657b2ee1d653926f09cc52da2faed
Reviewed-on: https://boringssl-review.googlesource.com/4329
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/crypto/rand/hwrand.c b/crypto/rand/hwrand.c
index 0d2833a..c5bace8 100644
--- a/crypto/rand/hwrand.c
+++ b/crypto/rand/hwrand.c
@@ -27,7 +27,7 @@
 }
 
 /* CRYPTO_rdrand is defined in asm/rdrand-x86_64.pl */
-extern uint64_t CRYPTO_rdrand();
+extern uint64_t CRYPTO_rdrand(void);
 
 void CRYPTO_hwrand(uint8_t *buf, size_t len) {
   while (len >= 8) {
diff --git a/crypto/rand/rand.c b/crypto/rand/rand.c
index 6655827..ae30edb 100644
--- a/crypto/rand/rand.c
+++ b/crypto/rand/rand.c
@@ -72,7 +72,7 @@
                              const uint8_t key[32], const uint8_t nonce[8],
                              size_t counter);
 
-int RAND_bytes(uint8_t *buf, const size_t len) {
+int RAND_bytes(uint8_t *buf, size_t len) {
   if (len == 0) {
     return 1;
   }