timer: use an inline function for free

Similarly to allocation, do it from an inline function. This allows
tests to only use the headers for allocation/free of timer.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

include/qemu/timer.h

@@ -610,7 +610,10 @@ void timer_deinit(QEMUTimer *ts);
  *
  * Free a timer (it must not be on the active list)
  */
-void timer_free(QEMUTimer *ts);
+static inline void timer_free(QEMUTimer *ts)
+{
+    g_free(ts);
+}
 
 /**
  * timer_del:

util/qemu-timer.c

@@ -355,11 +355,6 @@ void timer_deinit(QEMUTimer *ts)
     ts->timer_list = NULL;
 }
 
-void timer_free(QEMUTimer *ts)
-{
-    g_free(ts);
-}
-
 static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
 {
     QEMUTimer **pt, *t;