V8 Buildbot: Fix compilation on arm64 asan builder.
V8 Buildbot: Fix compilation on arm64 asan builder.

The specification host_arch=x86_64 is not recognized by gyp.
Like that, some conditions that set the path to the bundled
binutils aren't met and the path is wrong. The system
binutils are used, which leads to compilation errors.

BUG=412706
TBR=inferno@chromium.org, thakis@chromium.org, glider@chromium.org, jochen@chromium.org,

Review URL: https://codereview.chromium.org/1125133004

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@295225 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build