[tracker] Add AC_CACHE_CHECK magic around ioprio checking.

[John Carr <johncarr src gnome org>]

commit 8a798bc84e372d22084737f1adedfd29504391ee
Author: John Carr <john carr unrouted co uk>
Date:   Tue Nov 3 01:18:26 2009 +0000

    Add AC_CACHE_CHECK magic around ioprio checking.
    
    Having the cache check allows the end user to set whether ioprio
    is available or not. Without this cross-compilation is not
    possible as there is no way to run the test program.

 configure.ac |   24 +++++++++++-------------
 1 files changed, 11 insertions(+), 13 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 441b4b8..fca54b9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1164,17 +1164,15 @@ AM_CONDITIONAL(HAVE_LIBVORBIS, test "x$have_libvorbis" = "xyes")
 # Check ioprio support
 ####################################################################
 
-AC_MSG_CHECKING([[ioprio support]])
-have_ioprio=no
-
-AC_RUN_IFELSE(
-[AC_LANG_PROGRAM([[
+AC_CACHE_CHECK([if we have ioprio],[tracker_cv_have_ioprio],
+  [AC_RUN_IFELSE(
+    [AC_LANG_PROGRAM([[
 	#include <stdlib.h>
 	#include <errno.h>
 	#include <sys/syscall.h>
 	#include <unistd.h>
-]], 
-[[
+      ]], 
+      [[
         inline int ioprio_get (int which, int who) 
 	{
 	       return syscall (__NR_ioprio_get, which, who);
@@ -1184,16 +1182,16 @@ AC_RUN_IFELSE(
 	{
 	       return ioprio_get (1, 0);
 	}
-]]
-)],
-[have_ioprio=yes],[])
+      ]])],
+    [tracker_cv_have_ioprio=yes],
+    [tracker_cv_have_ioprio=no],
+    [AC_MSG_ERROR([cross-compiling: please set 'tracker_cv_have_ioprio'])])
+  ])
 
-if test "$have_ioprio" = "yes" ; then
+if test "x$tracker_cv_have_ioprio" = "xyes" ; then
    AC_DEFINE(HAVE_IOPRIO, 1, [Define if we have ioprio])
 fi
 
-AC_MSG_RESULT([$have_ioprio])
-
 ##################################################################
 # Check for exempi
 ##################################################################