gluster: Use pkg-config to configure GlusterFS block driver

Use pkg-config to determine the version and library dependency
for GlusterFS block driver.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/configure b/configure
index 9e1cd19..cf13493 100755
--- a/configure
+++ b/configure
@@ -2570,23 +2570,18 @@
 ##########################################
 # glusterfs probe
 if test "$glusterfs" != "no" ; then
-  cat > $TMPC <<EOF
-#include <glusterfs/api/glfs.h>
-int main(void) {
-    (void) glfs_new("volume");
-    return 0;
-}
-EOF
-  glusterfs_libs="-lgfapi -lgfrpc -lgfxdr"
-  if compile_prog "" "$glusterfs_libs" ; then
-    glusterfs=yes
+  if $pkg_config --atleast-version=3 glusterfs-api >/dev/null 2>&1; then
+    glusterfs="yes"
+    glusterfs_cflags=`$pkg_config --cflags glusterfs-api 2>/dev/null`
+    glusterfs_libs=`$pkg_config --libs glusterfs-api 2>/dev/null`
+    CFLAGS="$CFLAGS $glusterfs_cflags"
     libs_tools="$glusterfs_libs $libs_tools"
     libs_softmmu="$glusterfs_libs $libs_softmmu"
   else
     if test "$glusterfs" = "yes" ; then
       feature_not_found "GlusterFS backend support"
     fi
-    glusterfs=no
+    glusterfs="no"
   fi
 fi