Merging r245365 and r245369:

------------------------------------------------------------------------
r245365 | majnemer | 2015-08-18 15:07:25 -0700 (Tue, 18 Aug 2015) | 4 lines

[InstSimplify] Don't assume getAggregateElement will succeed

It isn't always possible to get a value from getAggregateElement.
This fixes PR24488.
------------------------------------------------------------------------

------------------------------------------------------------------------
r245369 | majnemer | 2015-08-18 15:18:22 -0700 (Tue, 18 Aug 2015) | 3 lines

[InstSimplify] Remove unused variable

No functionality change is intended.
------------------------------------------------------------------------

llvm-svn: 245572