git: disable git-gui if there is no tcl/tk support

develop/git/git.conf

@@ -2,7 +2,7 @@
 # This copyright note is auto-generated by ./scripts/Create-CopyPatch.
 #
 # Filename: package/.../git/git.conf
-# Copyright (C) 2007 The OpenSDE Project
+# Copyright (C) 2007 - 2009 The OpenSDE Project
 #
 # More information can be found in the files COPYING and README.
 #
@@ -12,6 +12,11 @@
 # GNU General Public License can be found in the file COPYING.
 # --- SDE-COPYRIGHT-NOTE-END ---
 
+# disable git-gui if there is no tcl/tk support
+if ! pkginstalled tk; then
+	var_append extraconfopt ' ' "--without-tcltk"
+fi
+
 if pkginstalled asciidoc; then
 	var_append makeopt ' ' 'doc'
 	var_append makeinstopt ' ' 'install-doc'