nasmlib.c: log nasm_free() before calling free()

If we're logging nasm_free(), then log it before we actually call
free(); that way we can find out what the last thing was if free()
crashes.

nasmlib.c

@@ -96,10 +96,10 @@ void nasm_free(void *q)
 #endif
 {
     if (q) {
-        free(q);
 #ifdef LOGALLOC
         fprintf(logfp, "%s %d free(%p)\n", file, line, q);
 #endif
+        free(q);
     }
 }