don't build wxGUI manual page as separate commands (sync'ed with develbr6)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@31178 15284696-431f-4ddb-bdfa-cd5b030d7da7

tools/build_html_index.sh

@@ -17,7 +17,7 @@ helptext.html \
 r.watershed.ram \
 r.watershed.seg \
 gis.m \
-wxGUI.*html \
+wxGUI.* \
 d.paint.labels \
 p.out.vrml \
 r.cats"