Merging r195379:

Merging r195379:
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r195379 | hans | 2013-11-21 14:47:21 -0800 (Thu, 21 Nov 2013) | 7 lines

CMake: Some changes to package version names:

- Allow overriding PACKAGE_VERSION from the command-line
- Use PACKAGE_VERSION to set CPACK_PACKAGE_VERSION (used by the Win installer)
- Don't include the version number in the CPack install dir or registry key.

Differential revision: http://llvm-reviews.chandlerc.com/D2245
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@195674 91177308-0d34-0410-b5e6-96231b3b80d8