Upgrade to regalloc2 0.1.3. (#4157)

* Upgrade to regalloc2 0.1.3.

This pulls in bytecodealliance/regalloc2#49, which slightly improves
codegen in some cases where a safepoint (for reference-typed values)
occurs in the same liverange as a register-constrained use. For
example, in bytecodealliance/wasmtime#3785, an extra move instruction
appeared and a callee-save register was used (necessitating a more
expensive prologue) because of suboptimal splitting heuristics, which
this PR fixes. The updated RA2 heuristics appear to have no measured
downsides in existing benchmarks and improve the manually-observed
codegen issue.

* Update filetests where regalloc2 improvement altered behavior with reftypes.

Cargo.lock

@@ -2351,9 +2351,9 @@ dependencies = [
 
 [[package]]
 name = "regalloc2"
-version = "0.1.2"
+version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ec1c2e4f4b879982653d243d9561d9f49004ce15a47e9682ad1f6d53a06aac0"
+checksum = "904196c12c9f55d3aea578613219f493ced8e05b3d0c6a42d11cb4142d8b4879"
 dependencies = [
  "fxhash",
  "log",