[GlobalISel][AArch64] Legalize + select G_FRINT

Exactly the same as G_FCEIL, G_FABS, etc.

Add tests for the fp16/nofp16 behaviour, update arm64-vfloatintrinsics, etc.

Differential Revision: https://reviews.llvm.org/D60895

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358799 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed