Back out D66983, "[WebAssembly] Add wasm-specific vector shuffle builtin and
Fix shuffle intrinsic tests. Since they are compiled with -O2 masks need to be
updated as well, otherwise optimizer would replace second operand with
Convert shuffle intrinsic codegen tests to use shufflevector and move them to
a separate file. This also requires some mask updates to avoid invalid
shufflevector use and to make sure both operands get picked up.
This reverts commit 8e3e56f2a36701480eeb65e426701d5a9025cc59.