Merge r338941 r338602 into the 7.0 branch : [constexpr] Support for constant evaluation of __builtin_memcpy and

[tstellar]

Bugzilla Link	39791
Resolution	WONTFIX
Resolved on	Nov 26, 2018 20:04
Version	7.0
OS	All
Blocks	#38454
CC	@zygoloid,@smeenai
Fixed by commit(s)	r338941 r338602

Extended Description

Is it OK to merge the following revision(s) to the 7.0 branch?

[tstellar]

https://reviews.llvm.org/rL338941

[tstellar]

https://reviews.llvm.org/rL338602

[zygoloid]

The revert was already merged in r338674. I don't think we should take the reinstatement of the feature for version 7.

[zygoloid]

The necessary revert was merged for the 7.0 release; taking the revert of the revert would amount to taking a new feature for 7.0.1, so let's not.