[Win] Use RC_PROJECTBUILDVERSION as build portion of version

[Win] Use RC_PROJECTBUILDVERSION as build portion of version
https://bugs.webkit.org/show_bug.cgi?id=135478

Reviewed by David Kilzer.

Tools:
Add new test suite for the version-stamp program.

* Scripts/webkitperl/auto-version_unittest/versionStampTests.pl: Added.

WebKitLibraries:
* win/tools/scripts/version-stamp.pl: Check environment for
RC_PROJECTBUILDVERSION, and use it for the build portion of
the file version resource. Otherwise, use the __VERSION_BUILD__
value we calculated from the version string.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@171903 268f45cc-cd09-0410-ab3c-d52691b4dbfc