[WebAssembly] Restore __stack_pointer after catch instructions

Summary:
After the stack is unwound due to a thrown exception, the
`__stack_pointer` global can point to an invalid address. This inserts
instructions that restore `__stack_pointer` global.

Reviewers: jgravelle-google, dschuff

Subscribers: mgorny, sbc100, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D50980

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@340339 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed