Before this change, 'wasmer run --backend=llvm some-simd.wasm' would run without complaint.
Also, note that the flag is not part of the cache key, so after any successful run, we can run it again without passing the flag.
These is one test failure remaining with V128 global variables.
* Fix trunc_sat. We need both the largest float that can be converted to an int
and the largest int, they are not the same number.
* Implement calling of functions that take V128 by passing in two i64's.
* Improve support for V128 in spectests. Parse binary modules with the same
features as the outer spectest. Fix compilation error involving Result in
emitted .rs file. Handle V128 in more cases when producing .rs file. Parse
the wast script with SIMD enabled.
* Adjust the WAVM spectest so that it parses with WABT and mostly passes with
wasmer. Wabt is particular about ints not having decimal places and floats
having decimal places. Wasmer does not support mutable globals or shared
memory. Tests of shuffles are disabled. Some assert_invalid tests that wabt
won't even parse are disabled.
