Handle -G output_dir=foo as well as -Goutput_dir=foo.
I'm not sure how common this case is but we have
NaCl SDK bot that do this.
Getting this wrong results in windows toolchain being
installed in 'out/' (which doesn't necessarily exist)
rather than the output_dir tree and gyp uses.
Add unittests for the affected parts of gyp_chromium.
BUG=454594
Review URL: https://codereview.chromium.org/896663002
Cr-Original-Commit-Position: refs/heads/master@{#314381}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 10ef1e2aa8ebb806ccfe7c52235f0fb76564ee2c
daniimms
sbc