linux-user: support timerfd_{create, gettime, settime} syscalls

Adds support for the timerfd_create, timerfd_gettime & timerfd_settime
syscalls, allowing use of timerfds by target programs.

v2: By Riku - added configure check for timerfd and ifdefs
for benefit of old distributions like RHEL5.

Signed-off-by: Paul Burton <paul@archlinuxmips.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
diff --git a/configure b/configure
index 283c71c..3d0ab1b 100755
--- a/configure
+++ b/configure
@@ -3456,6 +3456,20 @@
   sendfile=yes
 fi
 
+# check for timerfd support (glibc 2.8 and newer)
+timerfd=no
+cat > $TMPC << EOF
+#include <sys/timerfd.h>
+
+int main(void)
+{
+    return(timerfd_create(CLOCK_REALTIME, 0));
+}
+EOF
+if compile_prog "" "" ; then
+  timerfd=yes
+fi
+
 # Check if tools are available to build documentation.
 if test "$docs" != "no" ; then
   if has makeinfo && has pod2man; then
@@ -4524,6 +4538,9 @@
 if test "$sendfile" = "yes" ; then
   echo "CONFIG_SENDFILE=y" >> $config_host_mak
 fi
+if test "$timerfd" = "yes" ; then
+  echo "CONFIG_TIMERFD=y" >> $config_host_mak
+fi
 if test "$inotify" = "yes" ; then
   echo "CONFIG_INOTIFY=y" >> $config_host_mak
 fi