x64: Shrink Inst from 72 to 48 bytes (#4514)

https://github.com/bytecodealliance/wasmtime/pull/4514

cranelift/codegen/src/isa/x64/inst.isle

@@ -371,8 +371,7 @@
                     (tmp1 WritableReg)
                     (tmp2 WritableReg)
                     (default_target MachLabel)
-                    (targets VecMachLabel)
-                    (targets_for_term VecMachLabel))
+                    (targets BoxVecMachLabel))
 
        ;; Indirect jump: jmpq (reg mem).
        (JmpUnknown (target RegMem))
@@ -504,6 +503,8 @@
 
 (type BoxCallInfo extern (enum))
 
+(type BoxVecMachLabel extern (enum))
+
 ;; Get the `OperandSize` for a given `Type`, rounding smaller types up to 32 bits.
 (decl operand_size_of_type_32_64 (Type) OperandSize)
 (extern constructor operand_size_of_type_32_64 operand_size_of_type_32_64)