[WebAssembly] Add data size and alignement to linking section

The overal size of the data section (including BSS)
is otherwise not included in the wasm binary.

Differential Revision: https://reviews.llvm.org/D34657

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306459 91177308-0d34-0410-b5e6-96231b3b80d8
13 files changed