[WebAssembly] Print a debug message at the start of each pass

Summary:
Looks like many passes print its pass description as a debug message at
the start of each pass, so added that to (mostly newly added) other
passes as well.

Reviewers: dschuff

Subscribers: jgravelle-google, sbc100, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D56142

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350771 91177308-0d34-0410-b5e6-96231b3b80d8
10 files changed