Little detection change proposal.

As pointed out, the further path is called by open rather than shm_open.

Author: devnexen

ext/opcache/config.m4

@@ -294,7 +294,7 @@ int main() {
   char *shm;
   char tmpname[4096];
 
-  sprintf(tmpname,"/opcache.test.shm.%dXXXXXX", getpid());
+  sprintf(tmpname,"opcache.test.shm.%dXXXXXX", getpid());
   if (mktemp(tmpname) == NULL) {
     return 1;
   }