Do not define use_clipboard_aurax11 on ozone builds

On Ozone builds clipboard_aurax11 is excluded since Ozone
builds should not pull any X11 dependencies.

This patch fixes failing ui_unittests build on Ozone.

BUG=

Review URL: https://codereview.chromium.org/102163005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241390 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241390
Pass the path to the compiler from gyp to instrumented build script.

Now it does not require CC and CXX to be set before running "gclient runhooks"

BUG=313751
R=glider@chromium.org,thakis@chromium.org
TBR=cpu@chromium.org

Review URL: https://codereview.chromium.org/111553009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241392 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241392