Make it so zlib's submodule being dirty is ignored.
Make it so zlib's submodule being dirty is ignored.

(This is because of what I mentioned in the last commit, where zlib's CMake script modifies a file in the submodule.)

--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,7 @@
 [submodule "src/in_xsf_framework/zlib"]
 	path = src/in_xsf_framework/zlib
 	url = https://github.com/madler/zlib
+	ignore = dirty
 [submodule "src/in_xsf_framework/wxWidgets"]
 	path = src/in_xsf_framework/wxWidgets
 	url = https://github.com/wxWidgets/wxWidgets