Merging r326172:

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r326172 | mstorsjo | 2018-02-26 22:26:35 -0800 (Mon, 26 Feb 2018) | 7 lines

[MinGW] Ignore the --start-group --end-group parameters

These are required for handling circular dependencies between
static libraries, which is something that lld-link always does without
any extra parameters.

Differential Revision: https://reviews.llvm.org/D43786
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llvm-svn: 332044