acc: use gmtime_r() for a safer multi-thread usage

src/modules/acc/acc_cdr.c

@@ -141,7 +141,7 @@ static int db_write_cdr( struct dlg_cell* dialog,
 	long long_val;
 	double double_val;
 	char * end;
-	struct tm *t;
+	struct tm t;
 	char cdr_time_format_buf[MAX_CDR_CORE][TIME_STR_BUFFER_SIZE];
 
 	if(acc_cdrs_table.len<=0)
@@ -191,9 +191,9 @@ static int db_write_cdr( struct dlg_cell* dialog,
 				}
 				if (acc_time_mode==4) {
 					VAL_TYPE(db_cdr_vals+i)=DB1_STRING;
-					t = gmtime(&timeval_val.tv_sec);
+					gmtime_r(&timeval_val.tv_sec, &t);
 					/* Convert time_t structure to format accepted by the database */
-					if (strftime(cdr_time_format_buf[i], TIME_STR_BUFFER_SIZE, TIME_STRING_FORMAT, t) <= 0) {
+					if (strftime(cdr_time_format_buf[i], TIME_STR_BUFFER_SIZE, TIME_STRING_FORMAT, &t) <= 0) {
 						cdr_time_format_buf[i][0] = '\0';
 					}