This patch implements, for aarch64, the following wasm SIMD extensions
i32x4.dot_i16x8_s instruction
https://github.com/WebAssembly/simd/pull/127
It also updates dependencies as follows, in order that the new instruction can
be parsed, decoded, etc:
wat to 1.0.27
wast to 26.0.1
wasmparser to 0.65.0
wasmprinter to 0.2.12
The changes are straightforward:
* new CLIF instruction `widening_pairwise_dot_product_s`
* translation from wasm into `widening_pairwise_dot_product_s`
* new AArch64 instructions `smull`, `smull2` (part of the `VecRRR` group)
* translation from `widening_pairwise_dot_product_s` to `smull ; smull2 ; addv`
There is no testcase in this commit, because that is a separate repo. The
implementation has been tested, nevertheless.