[WebAssembly] Register wasm passes with the PassRegistry

Summary:
This exposes WebAssembly passes for use on the command line (as
arguments to -print-before and the like).

Reviewers: dschuff, sunfish

Subscribers: MatzeB, jfb, sbc100, llvm-commits, aheejin

Differential Revision: https://reviews.llvm.org/D45103

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@328901 91177308-0d34-0410-b5e6-96231b3b80d8
21 files changed