Revert "I need this change to create Windows 8.1/Windows Phone 8.1 projects that compile modules that can be consumed by Windows Store Applications (WinRT)."

This reverts commit 397b1c684b0b07a38f485f091cc4394a3d733334.

Failing on win64 bots per http://build.chromium.org/p/tryserver.nacl/builders/gyp-win64/builds/1896

BUG=

Review URL: https://codereview.chromium.org/596023003

git-svn-id: http://gyp.googlecode.com/svn/trunk@1983 78cadc50-ecff-11dd-a971-7dbc132099af
ninja win: Add support for 'CallingConvention'

Each calling convention decorates C functions in a different way, so we can use
that to test the flag.

BUG=
R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/597993003

git-svn-id: http://gyp.googlecode.com/svn/trunk@1984 78cadc50-ecff-11dd-a971-7dbc132099af