[WebAssembly] Add shared memory support to limits field

Support the IS_SHARED bit in the memory limits flag word.
The compiler does not create object files with memory definitions,
but the field is used by the linker.

Differential Revision: https://reviews.llvm.org/D54131

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346246 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed