Use safer sizeof variant in malloc

For a local variable:
        TYPE *p;
Allocations like this are "risky":
        p = OPENSSL_malloc(sizeof(TYPE));
if the type of p changes, and the malloc call isn't updated, you
could get memory corruption.  Instead do this:
        p = OPENSSL_malloc(sizeof(*p));
Also fixed a few memset() calls that I noticed while doing this.

Reviewed-by: Richard Levitte <levitte@openssl.org>

ssl/s3_lib.c

@@ -3098,9 +3098,9 @@ int ssl3_new(SSL *s)
 {
     SSL3_STATE *s3;
 
-    if ((s3 = OPENSSL_malloc(sizeof *s3)) == NULL)
+    if ((s3 = OPENSSL_malloc(sizeof(*s3))) == NULL)
         goto err;
-    memset(s3, 0, sizeof *s3);
+    memset(s3, 0, sizeof(*s3));
     s->s3 = s3;
     
 #ifndef OPENSSL_NO_SRP
@@ -3137,7 +3137,7 @@ void ssl3_free(SSL *s)
 #ifndef OPENSSL_NO_SRP
     SSL_SRP_CTX_free(s);
 #endif
-    OPENSSL_clear_free(s->s3, sizeof *s->s3);
+    OPENSSL_clear_free(s->s3, sizeof(*s->s3));
     s->s3 = NULL;
 }
 
@@ -3174,7 +3174,7 @@ void ssl3_clear(SSL *s)
         s->s3->alpn_selected = NULL;
     }
 #endif
-    memset(s->s3, 0, sizeof *s->s3);
+    memset(s->s3, 0, sizeof(*s->s3));
     s->s3->init_extra = init_extra;
 
     ssl_free_wbio_buffer(s);