Correct handling of __VERSION_TEXT__ for 4+-tuple versions

Correct handling of __VERSION_TEXT__ for 4+-tuple versions
https://bugs.webkit.org/show_bug.cgi?id=135161
<rdar://problem/17763546>

Reviewed by David Kilzer.

Tools:
* Scripts/webkitperl/auto-version_unittest/autoVersionTests.pl:
Add additional test cases to catch errors in multiple-tuple
version string handling.

WebKitLibraries:
Revise the auto-version.pl script to properly handle version
strings with 4 (or more) version tuples. Previously these were
being truncated from the version.

* win/tools/scripts/auto-version.pl:
(splitVersion): Return truncated version of
overall version string.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@171351 268f45cc-cd09-0410-ab3c-d52691b4dbfc