cmd/objdump: print full disassembly when testing with -v

It is helpful for debugging.

Change-Id: Idd566d312037420f8341fcf502a45410a8497798
Reviewed-on: https://go-review.googlesource.com/c/go/+/353878
Trust: Josh Bleecher Snyder <[email protected]>
Run-TryBot: Josh Bleecher Snyder <[email protected]>
Reviewed-by: Brad Fitzpatrick <[email protected]>

src/cmd/objdump/objdump_test.go

@@ -228,7 +228,7 @@ func testDisasm(t *testing.T, srcfname string, printCode bool, printGnuAsm bool,
  }
  }
 
- if !ok {
+ if !ok || testing.Verbose() {
  t.Logf("full disassembly:\n%s", text)
  }
 }