Reland "[WebAssembly] Add support for naming wasm data segments"

Add adds support for naming data segments.  This is useful
useful linkers so that they can merge similar sections.

Differential Revision: https://reviews.llvm.org/D37886

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313795 91177308-0d34-0410-b5e6-96231b3b80d8
14 files changed