tools: add configure option for libfsimage

The only in-tree user of libfsimage is pygrub. Now that it is possible
to disable the build of pygrub, the same should be possible for
libfsimage.

Add an option for controlling the build of libfsimage. The default is
on if pygrub is being built, and off if it isn't. Without pygrub the
build of libfsimage can be enabled via --enable-libfsimage.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>

config/Tools.mk.in

@@ -49,6 +49,7 @@ CONFIG_QEMUU_EXTRA_ARGS:= @EXTRA_QEMUU_CONFIGURE_ARGS@
 CONFIG_LIBNL        := @libnl@
 CONFIG_GOLANG       := @golang@
 CONFIG_PYGRUB       := @pygrub@
+CONFIG_LIBFSIMAGE   := @libfsimage@
 
 CONFIG_SYSTEMD      := @systemd@
 SYSTEMD_CFLAGS      := @SYSTEMD_CFLAGS@