GN: Fix cross ARM64 and cross MIPS builds.

tools/gn.py

Index: tools/gn.py
diff --git a/tools/gn.py b/tools/gn.py
index 1e5120b927b06d68eece76e4d65f49bb156e50fa..0f55fce78d9432a4e881d424ebbaf5f27bc85f79 100755
--- a/tools/gn.py
+++ b/tools/gn.py
@@ -143,7 +143,7 @@ def to_gn_args(args, mode, arch, target_os):
   # Force -mfloat-abi=hard and -mfpu=neon on Linux as we're specifying
   # a gnueabihf compiler in //build/toolchain/linux BUILD.gn.
   # TODO(zra): This will likely need some adjustment to build for armv6 etc.
-  hard_float = (gn_args['target_cpu'].startswith('arm') and
+  hard_float = ((gn_args['target_cpu'] == 'arm') and

[zra, 2017/01/18 03:21:33]

Add a TODO that this will need to change if we want to continue supporting armv6
and armv5te, or refine this test to include those but exclude arm64.

[rmacnak, 2017/01/20 22:54:47]

Added branches that throw with an unimplemented message for armv6/5te.

                 (gn_args['target_os'] == 'linux'))
   if hard_float:
     gn_args['arm_float_abi'] = 'hard'