Post release tag bump.

configure.ac.in

@@ -7,7 +7,7 @@ m4_define([xfwm4_version_major], [4])
 m4_define([xfwm4_version_minor], [9])
 m4_define([xfwm4_version_micro], [0])
 m4_define([xfwm4_version_build], [@REVISION@])
-m4_define([xfwm4_version_tag],   [])
+m4_define([xfwm4_version_tag],   [git])
 m4_define([xfwm4_version], [xfwm4_version_major().xfwm4_version_minor().xfwm4_version_micro()ifelse(xfwm4_version_tag(), [git], [xfwm4_version_tag().xfwm4_version_build()], [xfwm4_version_tag()])])
 
 m4_define([gtk_minimum_version], [2.14.0])