Merging r257977:

Merging r257977:
------------------------------------------------------------------------
r257977 | kfischer | 2016-01-15 17:11:33 -0800 (Fri, 15 Jan 2016) | 1 line

[DwarfDebug] Move MergeValues to .cpp, NFC
------------------------------------------------------------------------
Merging r257979:
------------------------------------------------------------------------
r257979 | kfischer | 2016-01-15 17:15:32 -0800 (Fri, 15 Jan 2016) | 11 lines

[DwarfDebug] Don't merge DebugLocEntries if their pieces overlap

Summary:
Later in DWARF emission we check that DebugLocEntries have
non-overlapping pieces, so we should create any such entries
by merging here.

Fixes PR26163.

Reviewers: aprantl
Differential Revision: http://reviews.llvm.org/D16249
------------------------------------------------------------------------

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_38@258267 91177308-0d34-0410-b5e6-96231b3b80d8