[CVP] Reenable nowrap flag inference

Inference of nowrap flags in CVP has been disabled, because it
triggered a bug in LFTR (https://bugs.llvm.org/show_bug.cgi?id=31181).
This issue has been fixed in D60935, so we should be able to reenable
nowrap flag inference now.

Differential Revision: https://reviews.llvm.org/D62776

llvm-svn: 364228