Merging r270821:

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r270821 | hfinkel | 2016-05-25 23:48:14 -0500 (Wed, 25 May 2016) | 6 lines

Add an assembly __kmp_invoke_microtask for ppc64[le]

Clang no longer restricts itself to generating microtasks with a small number
of arguments, and so an assembly implementation is required to prevent hitting
the parameter limit present in the C implementation. This adds an
implementation for ppc64[le].
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llvm-svn: 271580