configure: Add a config option for GlusterFS as block backend

GlusterFS support in QEMU depends on libgfapi, libgfrpc and
libgfxdr provided by GlusterFS.
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

configure

@@ -219,6 +219,7 @@ want_tools="yes"
 libiscsi=""
 coroutine=""
 seccomp=""
+glusterfs=""
 
 # parse CC options first
 for opt do
@@ -856,6 +857,10 @@ for opt do
   ;;
   --disable-seccomp) seccomp="no"
   ;;
+  --disable-glusterfs) glusterfs="no"
+  ;;
+  --enable-glusterfs) glusterfs="yes"
+  ;;
   *) echo "ERROR: unknown option $opt"; show_help="yes"
   ;;
   esac
@@ -1128,6 +1133,8 @@ echo "  --disable-seccomp        disable seccomp support"
 echo "  --enable-seccomp         enables seccomp support"
 echo "  --with-coroutine=BACKEND coroutine backend. Supported options:"
 echo "                           gthread, ucontext, sigaltstack, windows"
+echo "  --enable-glusterfs       enable GlusterFS backend"
+echo "  --disable-glusterfs      disable GlusterFS backend"
 echo ""
 echo "NOTE: The object files are built at the place where configure is launched"
 exit 1
@@ -2303,6 +2310,29 @@ EOF
   fi
 fi
 
+##########################################
+# 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
+    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
+  fi
+fi
+
 #
 # Check for xxxat() functions when we are building linux-user
 # emulator.  This is done because older glibc versions don't
@@ -3170,6 +3200,7 @@ echo "libiscsi support  $libiscsi"
 echo "build guest agent $guest_agent"
 echo "seccomp support   $seccomp"
 echo "coroutine backend $coroutine_backend"
+echo "GlusterFS support $glusterfs"
 
 if test "$sdl_too_old" = "yes"; then
 echo "-> Your SDL version is too old - please upgrade to have SDL support"
@@ -3516,6 +3547,10 @@ if test "$has_environ" = "yes" ; then
   echo "CONFIG_HAS_ENVIRON=y" >> $config_host_mak
 fi
 
+if test "$glusterfs" = "yes" ; then
+  echo "CONFIG_GLUSTERFS=y" >> $config_host_mak
+fi
+
 # USB host support
 case "$usb" in
 linux)