Revert commits 5685 to 5688 committed by mistake

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5691 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/vl.c b/vl.c
index 24c9c32..7bcffd3 100644
--- a/vl.c
+++ b/vl.c
@@ -1403,7 +1403,7 @@
 
 #define RTC_FREQ 1024
 
-void enable_sigio_timer(int fd)
+static void enable_sigio_timer(int fd)
 {
     struct sigaction act;