[IntrinsicEmitter] Add overloaded type VecOfBitcastsToInt for SVE intrinsics

Summary:
This allows intrinsics such as the following to be defined:
 - declare <n x 4 x i32> @llvm.something.nxv4f32(<n x 4 x i32>, <n x 4 x i1>, <n x 4 x float>)

...where <n x 4 x i32> is derived from <n x 4 x float>, but
the element needs bitcasting to int.

Reviewers: c-rhodes, sdesmalen, rovka

Reviewed By: c-rhodes

Subscribers: tschuett, hiraditya, jdoerfert, llvm-commits, cfe-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68021

llvm-svn: 373437