patch-tool-mxe: add ignored files to initial commit

"git add -f" allows adding otherwise ignored files.

Archives might include .gitignore files specifying files to be ignored
by git, i.e., not added to the project's repository. Since the patch
tool uses git to manage patches that may affect these "ignored" files,
they should not be excluded from the working repository created by the
patch tool.

mxe.patch.mk

@@ -25,7 +25,7 @@ define INIT_GIT
     find '$(call GIT_DIR,$(1))' -name .git -prune -exec sh -c 'mv "$$0" "$$0"_' {} \;
     # initialize git
     $(call GIT_CMD,$(1)) init
-    $(call GIT_CMD,$(1)) add -A
+    $(call GIT_CMD,$(1)) add -A -f
     $(call GIT_CMD,$(1)) commit -m "init"
     $(call GIT_CMD,$(1)) tag dist
 endef