Fix a false positive GCC5 warning.

sql/signal_handler.cc

@@ -191,16 +191,18 @@ extern "C" sig_handler handle_fatal_signal(int sig)
 
   if (dflt_key_cache && thread_scheduler)
   {
+    size_t used_mem=
+        (dflt_key_cache->key_cache_mem_size +
+         (global_system_variables.read_buff_size +
+          (size_t) global_system_variables.sortbuff_size) *
+             (thread_scheduler->max_threads + extra_max_connections) +
+         (max_connections + extra_max_connections) * sizeof(THD)) / 1024;
+
     my_safe_printf_stderr("It is possible that mysqld could use up to \n"
                           "key_buffer_size + "
                           "(read_buffer_size + sort_buffer_size)*max_threads = "
-                          "%zu K  bytes of memory\n",
-                          (dflt_key_cache->key_cache_mem_size +
-                           (global_system_variables.read_buff_size +
-                            (size_t)global_system_variables.sortbuff_size) *
-                           (thread_scheduler->max_threads + extra_max_connections) +
-                           (max_connections + extra_max_connections) *
-                           sizeof(THD)) / 1024);
+                          "%zu K  bytes of memory\n", used_mem);
+
     my_safe_printf_stderr("%s",
                           "Hope that's ok; if not, decrease some variables in "
                           "the equation.\n\n");