[ADT] IntervalMap: use AlignedCharArrayUnion.
[ADT] IntervalMap: use AlignedCharArrayUnion.

Currently IntervalMap would assert when used with keys bigger than host
pointers. This patch uses the AlignedCharArrayUnion functionality to
overcome that limitation.

Differential Revision: http://reviews.llvm.org/D8268

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@232079 91177308-0d34-0410-b5e6-96231b3b80d8

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