configure.ac: drop spurious bracket

Otherwise configure output looks like

    checking for library containing pam_open_session... -lpam
    ./configure: line 18064: ]: command not found
    checking for COLORD... yes

Signed-off-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Daniel Stone <daniels@collabora.com>

configure.ac

@@ -449,7 +449,7 @@ fi
 
 AM_CONDITIONAL(HAVE_PANGO, test "x$have_pango" = "xyes")
 if test "x$have_pango" = "xyes"; then
-  AC_DEFINE([HAVE_PANGO], [1], [Have pango])]
+  AC_DEFINE([HAVE_PANGO], [1], [Have pango])
 fi
 
 AM_CONDITIONAL(HAVE_CAIRO_GLESV2,