Fix buildpkg for osx.

buildpkg

@@ -4,6 +4,9 @@ tar zcvf nvidia-texture-tools-`cat VERSION`.tar.gz \
 	--exclude '.*' --exclude debian --exclude '*~' --exclude buildpkg \
 	--exclude 'build-*' --exclude data --exclude tags --exclude Makefile \
 	--exclude 'doc' --exclude 'nvidia-texture-tools-*.tar.gz' \
+    --exclude 'extern/skylight' --exclude 'extern/FreeImage' \
+    --exclude 'extern/atitc' --exclude 'extern/glew' \
+    --exclude 'extern/gnuwin32' \
 	--exclude '*.user' -s ',^,nvidia-texture-tools/,' *
 #   --exclude '*.user' --transform 's,^,nvidia-texture-tools/,' *
 #	--exclude '*.user' *