Change intermediate and output directories for 64bit VS build to different from x86 build. This su…

Change intermediate and output directories for 64bit VS build to different from x86 build.  This supports issue 12303010

BUG=166496

[Will Harris, 2013-02-20 23:27:13]

This change makes the build output/intermediate directories for VS2010 builds to
match those in Ninja e.g. they will be Debug_x64 and Release_x64 instead of the
same ones used for x86 builds.  The primary reason for this is
https://codereview.chromium.org/12303010/ which requires this change in order to
identify that it should take the 64bit version of libcmt instead of 32bit, but
really having a consistent build directory structure across ninja and VS2010
makes a lot of sense.  Note: same changes would also exist in third party repos
but not changing those.

[scottmg, 2013-02-20 23:32:42]

Hm, are we sure we shouldn't be getting rid of _x64 instead? -Dtarget_arch=x64
is how the other platforms do it, which switches what Debug/Release are.

[Will Harris, 2013-02-20 23:54:28]

On 2013/02/20 23:32:42, scottmg wrote:
> Hm, are we sure we shouldn't be getting rid of _x64 instead? -Dtarget_arch=x64
> is how the other platforms do it, which switches what Debug/Release are.

Decision was made not to make this change, instead to change
https://codereview.chromium.org/12303010/ to avoid having to detect platform
target by output directory name, and instead have this detected some other way