GN: aix port along with linux_s390x, linux_ppc64 and linux_ppc64le support.

Most of the porting involves files inside /base.

This also fixes build/build_config.h not identifying PPC architectures correctly. Finally, it adds aix support to files inside tools/gn/, including the bootstrap script.

R=machenbach@chromium.org, dpranke@chromium.org, adamk@chromium.org
BUG=706728

Review-Url: https://codereview.chromium.org/2807463004
Cr-Original-Commit-Position: refs/heads/master@{#467484}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 0088ee5017f4bef6c27243a54d8998f993db11b8
1 file changed