Cranelift: update to latest regalloc2: (#4324)

- Handle call instructions' clobbers with the clobbers API, using RA2's
  clobbers bitmask (bytecodealliance/regalloc2#58) rather than clobbers
  list;

- Pull in changes from bytecodealliance/regalloc2#59 for much more sane
  edge-case behavior w.r.t. liverange splitting.

cranelift/codegen/src/isa/x64/lower/isle.rs

@@ -18,7 +18,7 @@ use crate::{
         settings::Flags,
         unwind::UnwindInst,
         x64::{
-            inst::{args::*, regs},
+            inst::{args::*, regs, CallInfo},
             settings::Flags as IsaFlags,
         },
     },
@@ -26,8 +26,11 @@ use crate::{
         isle::*, AtomicRmwOp, InsnInput, InsnOutput, LowerCtx, VCodeConstant, VCodeConstantData,
     },
 };
+use std::boxed::Box;
 use std::convert::TryFrom;
 
+type BoxCallInfo = Box<CallInfo>;
+
 pub struct SinkableLoad {
     inst: Inst,
     addr_input: InsnInput,