Use capstone to validate precise-output tests (#5780)

Use the capstone library to disassemble precise-output tests, in addition to pretty-printing their vcode.

cranelift/filetests/filetests/egraph/multivalue.clif

@@ -1,6 +1,7 @@
 test compile precise-output
 set opt_level=speed
 set use_egraphs=true
+set machine_code_cfg_info=true
 target x86_64
 
 ;; We want to make sure that this compiles successfully, so we are properly
@@ -15,6 +16,7 @@ function u0:359(i64) -> i8, i8 system_v {
 		return v3, v4
 }
 
+; VCode:
 ;   pushq   %rbp
 ;   movq    %rsp, %rbp
 ; block0:
@@ -22,4 +24,13 @@ function u0:359(i64) -> i8, i8 system_v {
 ;   movq    %rbp, %rsp
 ;   popq    %rbp
 ;   ret
+; 
+; Disassembled:
+;   pushq %rbp
+;   movq %rsp, %rbp
+; block0: ; offset 0x4
+;   callq 9 ; reloc_external CallPCRel4 u0:521 -4
+;   movq %rbp, %rsp
+;   popq %rbp
+;   retq
 

cranelift/filetests/filetests/egraph/not_a_load.clif

@@ -13,6 +13,7 @@ function u0:1302(i64) -> i64 system_v {
     return v0
 }
 
+; VCode:
 ;   pushq   %rbp
 ;   movq    %rsp, %rbp
 ; block0:
@@ -21,4 +22,18 @@ function u0:1302(i64) -> i64 system_v {
 ;   movq    %rbp, %rsp
 ;   popq    %rbp
 ;   ret
+; 
+; Disassembled:
+;   pushq %rbp
+;   movq %rsp, %rbp
+; block0: ; offset 0x4
+;   movq (%rdi), %rax ; trap: heap_oob
+;   movq %rax, %rcx
+;   addq %rdi, %rcx
+;   lock cmpxchgq %rcx, (%rdi) ; trap: heap_oob
+;   jne 7
+;   movq %rdi, %rax
+;   movq %rbp, %rsp
+;   popq %rbp
+;   retq