[lld][WebAssembly] Prefer objdump -d over obj2yaml for tests. NFC

Now that we have https://reviews.llvm.org/D105539 we can
use objdump -d to actually check for instruction sequences
rather than binary blobs.

This is just an example of how to do that we should followup
with a wider ranging conversion of existing tests.

Differential Revision: https://reviews.llvm.org/D106897

Author: sbc100

lld/test/wasm/startstop.ll

@@ -2,6 +2,7 @@
 ; RUN: llc -filetype=obj %p/Inputs/explicit-section.ll -o %t2.o
 ; RUN: wasm-ld --export=get_start --export=get_end --export=foo --export=var1 %t.o %t2.o -o %t.wasm
 ; RUN: obj2yaml %t.wasm | FileCheck %s
+; RUN: llvm-objdump -d --no-show-raw-insn %t.wasm | FileCheck %s --check-prefix=ASM
 
 target triple = "wasm32-unknown-unknown"
 
@@ -23,31 +24,22 @@ define void @_start()  {
 entry:
   ret void
 }
-; CHECK:        - Type:            CODE
-; CHECK-NEXT:     Functions:
-; CHECK-NEXT:       - Index:           0
-; CHECK-NEXT:         Locals:          []
-; CHECK-NEXT:         Body:            4180888080000B
-; CHECK-NEXT:       - Index:           1
-; CHECK-NEXT:         Locals:          []
-; CHECK-NEXT:         Body:            4190888080000B
-; CHECK-NEXT:       - Index:           2
-; CHECK-NEXT:         Locals:          []
-; CHECK-NEXT:         Body:            0B
-; CHECK-NEXT:   - Type:            DATA
+
+;      CHECK:   - Type:            DATA
 ; CHECK-NEXT:     Segments:
 ; CHECK-NEXT:       - SectionOffset:   7
 ; CHECK-NEXT:         InitFlags:       0
 ; CHECK-NEXT:         Offset:
 ; CHECK-NEXT:           Opcode:          I32_CONST
 ; CHECK-NEXT:           Value:           1024
 ; CHECK-NEXT:         Content:         03000000040000002A0000002B000000
-; CHECK-NEXT:   - Type:            CUSTOM
-; CHECK-NEXT:     Name:            name
-; CHECK-NEXT:     FunctionNames:
-; CHECK-NEXT:       - Index:           0
-; CHECK-NEXT:         Name:            get_start
-; CHECK-NEXT:       - Index:           1
-; CHECK-NEXT:         Name:            get_end
-; CHECK-NEXT:       - Index:           2
-; CHECK-NEXT:         Name:            _start
+
+;       ASM: 00000001 <get_start>:
+; ASM-EMPTY:
+;  ASM-NEXT:        3:     i32.const 1024
+;  ASM-NEXT:        9:     end
+
+;       ASM: 0000000a <get_end>:
+; ASM-EMPTY:
+;  ASM-NEXT:        c:     i32.const 1040
+;  ASM-NEXT:       12:     end