Merging r303257:

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r303257 | kparzysz | 2017-05-17 09:25:09 -0400 (Wed, 17 May 2017) | 10 lines

[PPC] Properly update register save area offsets

The variables MinGPR/MinG8R were not updated properly when resetting the
offsets, which in the included testcase lead to saving the CR register
in the same location as R30.

This fixes another issue reported in PR26519.

Differential Revision: https://reviews.llvm.org/D33017

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llvm-svn: 304145