Failing Windows build

[Stephen Colebourne]

So my last attempt at building OpenJDK took a whole day to get
something thanks to a buggy script.

I've pulled again (ThreeTen repo) and spent another whole evening
watching the build churn incredibly slowly to a failure. Sorry if this
seems ranty, but this "new build" just seems very unreliable and very
slow to me:

make images NEWBUILD=true

Images.gmk:616: warning: ignoring old recipe for target `/release'
/usr/bin/mkdir: missing operand
Try `/usr/bin/mkdir --help' for more information.
Images.gmk:573: recipe for target `/ASSEMBLY_EXCEPTION' failed
make[2]: *** [/ASSEMBLY_EXCEPTION] Error 1
make[2]: *** Waiting for unfinished jobs....
/usr/bin/mkdir: missing operand
Try `/usr/bin/mkdir --help' for more information.
Images.gmk:573: recipe for target `/THIRD_PARTY_README' failed
make[2]: *** [/THIRD_PARTY_README] Error 1
/usr/bin/mkdir: missing operand
Try `/usr/bin/mkdir --help' for more information.
Images.gmk:573: recipe for target `/LICENSE' failed
make[2]: *** [/LICENSE] Error 1
BuildJdk.gmk:90: recipe for target `images' failed
make[1]: *** [images] Error 2
/cygdrive/c/dev/threeten/jdk8_310/ojdk//common/makefiles/Main.gmk:127:
recipe for target `images-only' failed
make: *** [images-only] Error 2

I would offer to re-run configure, but it takes too long to re-build
and I want to go to bed.
Stephen