Fix parallel build on MINGW

	When the build is running with a base ruby then generating `x64-ucrt-ruby320.rc`
	could fail due to a missing dependency to `x64-mingw-ucrt-fake.rb`.
	This commit adds this dependency.

	A failing build looks like so:
	```
	generating x64-mingw-ucrt-fake.rb
	generating x64-ucrt-ruby320.rc
	../snapshot-master/win32/resource.rb:in `require': cannot load such file -- ./x64-mingw-ucrt-fake (LoadError)
	make: *** [GNUmakefile:57: x64-ucrt-ruby320.rc] Error 1
	make: *** Waiting for unfinished jobs....
	linking miniruby.exe
	x64-mingw-ucrt-fake.rb updated
	```
	---
	 cygwin/GNUmakefile.in | 4 ++--
	 template/Makefile.in  | 1 +
	 2 files changed, 3 insertions(+), 2 deletions(-)