Second patch of patch series that improves MergeFunctions performance time from O(N*N) to
O(N*log(N)). The idea is to introduce total ordering among functions set.
It allows to build binary tree and perform function look-up procedure in O(log(N)) time. 

This patch description:
Introduced total ordering among constants implemented in cmpConstants method.
Method performs lexicographical comparison between constants represented as
hypothetical numbers of next format:
<bitcastability-trait><raw-bit-contents>

Please, read cmpConstants declaration comments for more details.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208173 91177308-0d34-0410-b5e6-96231b3b80d8
[BUG][REFACTOR]
1) Fix for printing debug locations for absolute paths.
2) Location printing is moved into public method DebugLoc::print() to avoid re-inventing the wheel.

Differential Revision: http://reviews.llvm.org/D3513




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208177 91177308-0d34-0410-b5e6-96231b3b80d8