This enables compiling V8 stand-alone for mips (big endian)
on an ia32 host with gn args:

custom_toolchain="//:mips-bundled"
v8_use_snapshot=false
v8_enable_i18n_support=false
icu_use_data_file=false
is_debug=false
target_cpu="mips"

Bug: chromium:632390
Change-Id: I0b59126d742a2979dd0fcbcdd3a574008a09479a
Reviewed-on: https://chromium-review.googlesource.com/904990Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51167}