Merging r258416 and r258428:

Merging r258416 and r258428:

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r258416 | spatel | 2016-01-21 10:01:57 -0800 (Thu, 21 Jan 2016) | 2 lines

make helper functions static; NFCI
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r258428 | spatel | 2016-01-21 12:19:54 -0800 (Thu, 21 Jan 2016) | 15 lines

[LibCallSimplifier] don't get fooled by a fake fmin()

This is similar to the bug/fix:
https://llvm.org/bugs/show_bug.cgi?id=26211
http://reviews.llvm.org/rL258325

The fmin() test case reveals another bug caused by sloppy
code duplication. It will crash without this patch because
fp128 is a valid floating-point type, but we would think
that we had matched a function that used doubles.

The new helper function can be used to replace similar
checks that are used in several other places in this file.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_38@258512 91177308-0d34-0410-b5e6-96231b3b80d8