Merging r357506:

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r357506 | atanasyan | 2019-04-02 11:03:31 -0700 (Tue, 02 Apr 2019) | 7 lines

[driver][mips] Check both `gnuabi64` and `gnu` suffixes in `getMultiarchTriple`

In case of N64 ABI toolchain paths migth have `mips-linux-gnuabi64`
or `mips-linux-gnu` directory regardless of selected environment.
Check both variants while detecting a multiarch triple.

Fix for the bug https://bugs.llvm.org/show_bug.cgi?id=41204
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llvm-svn: 358947