Remove erroneous uses of CXX / CXX_target / CXX_host from gyp.

Remove erroneous uses of CXX / CXX_target / CXX_host from gyp.

The current gyp config tries to test whether the compiler is an arm / mips
compiler and whether it supports -m32 / -m64 based on a test within gyp.
Unfortunately CXX / CXX_target / CXX_host are no no longer set early enough
in gyp for this to work, and so all of these tests were actually being done
using "$(which g++)" rather than the appropriate CXX_target / CXX_host compiler.

This change removes these dynamic tests and instead bases the decisions on
knowledge of the host / target / v8_target architecture combination.  The
the -m32/-m64 flags are set based on host_cxx_is_biarch / target_cxx_is_biarch,
which are set to reasonable defaults of only ia32/x64 or clang compilers
being build for biarch support.  The host_cxx_is_biarch / target_cxx_is_biarch
variables can be overriden if required.

BUG=384474
LOG=NO
R=jkummerow@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=22425

[rmcilroy, 2014-07-15 09:36:47]

Jacob, could you take a look please. Thanks.

[Jakob Kummerow, 2014-07-16 08:25:34]

LGTM. Let's see what breaks in the wild :-)

https://codereview.chromium.org/382343003/diff/40001/build/toolchain.gypi
File build/toolchain.gypi (right):

https://codereview.chromium.org/382343003/diff/40001/build/toolchain.gypi#new...
build/toolchain.gypi:472: ['_toolset=="target"', {
nit: this should have the same indentation as the '_toolset=="host"' line (I
think lines 467 through 483 all have one space too many).

[rmcilroy, 2014-07-16 09:20:26]

Thanks Jacob

https://codereview.chromium.org/382343003/diff/40001/build/toolchain.gypi
File build/toolchain.gypi (right):

https://codereview.chromium.org/382343003/diff/40001/build/toolchain.gypi#new...
build/toolchain.gypi:472: ['_toolset=="target"', {
On 2014/07/16 08:25:34, Jakob wrote:
> nit: this should have the same indentation as the '_toolset=="host"' line (I
> think lines 467 through 483 all have one space too many).

Done.

[rmcilroy, 2014-07-16 09:23:18]

Committed patchset #2 manually as r22425 (presubmit successful).