Don't cast |OPENSSL_malloc|/|OPENSSL_realloc| result.

C has implicit conversion of |void *| to other pointer types so these
casts are unnecessary. Clean them up to make the code easier to read
and to make it easier to find dangerous casts.

Change-Id: I26988a672e8ed4d69c75cfbb284413999b475464
Reviewed-on: https://boringssl-review.googlesource.com/7102
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/crypto/rsa/rsa.c b/crypto/rsa/rsa.c
index 6c28ad7..9ffea1f 100644
--- a/crypto/rsa/rsa.c
+++ b/crypto/rsa/rsa.c
@@ -76,7 +76,7 @@
 RSA *RSA_new(void) { return RSA_new_method(NULL); }
 
 RSA *RSA_new_method(const ENGINE *engine) {
-  RSA *rsa = (RSA *)OPENSSL_malloc(sizeof(RSA));
+  RSA *rsa = OPENSSL_malloc(sizeof(RSA));
   if (rsa == NULL) {
     OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE);
     return NULL;