Remove the default setting for clcompile_cmd in msvs-ninja

The 'msvs_external_builder_clcompile_cmd' logic is preserved, this commit
simply removes the default setting.  It can be restored by individual
developers based on personal preference.

BUG=352876
R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/246613003

git-svn-id: http://gyp.googlecode.com/svn/trunk@1901 78cadc50-ecff-11dd-a971-7dbc132099af
win: disable two flaky tests on gyp-win32

After much investigation (linked bug and earlier ps), I don't
really know much other than that these tests are failing when
the toolchain emits:

"LINK : unable to load ILK file; performing full link"

I haven't been able to figure out why that's happening though, so
I'm going to disable these two tests on x86 hosts so that the bots
aren't red.

I'm also going to add the diagnostic flag to the chromium build to
see if we can diagnose any unexpected incremental link failures.

R=thakis@chromium.org
BUG=365833 and https://groups.google.com/d/topic/gyp-developer/gKRi0DB-DWw/discussion

Review URL: https://codereview.chromium.org/247713002

git-svn-id: http://gyp.googlecode.com/svn/trunk@1902 78cadc50-ecff-11dd-a971-7dbc132099af