debug/pe: support windows/arm

Enable 'go tool objdump' to disassemble windows/arm images.

Updates #26148

Change-Id: I7d11226f01d92288061f8e25980334b9bd82c41f
Reviewed-on: https://go-review.googlesource.com/125649Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/debug/pe/file.go

@@ -91,7 +91,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 		return nil, err
 	}
 	switch f.FileHeader.Machine {
-	case IMAGE_FILE_MACHINE_UNKNOWN, IMAGE_FILE_MACHINE_AMD64, IMAGE_FILE_MACHINE_I386:
+	case IMAGE_FILE_MACHINE_UNKNOWN, IMAGE_FILE_MACHINE_ARMNT, IMAGE_FILE_MACHINE_AMD64, IMAGE_FILE_MACHINE_I386:
 	default:
 		return nil, fmt.Errorf("Unrecognised COFF file header machine value of 0x%x.", f.FileHeader.Machine)
 	}

src/debug/pe/pe.go

@@ -91,6 +91,7 @@ const (
 	IMAGE_FILE_MACHINE_AM33      = 0x1d3
 	IMAGE_FILE_MACHINE_AMD64     = 0x8664
 	IMAGE_FILE_MACHINE_ARM       = 0x1c0
+	IMAGE_FILE_MACHINE_ARMNT     = 0x1c4
 	IMAGE_FILE_MACHINE_ARM64     = 0xaa64
 	IMAGE_FILE_MACHINE_EBC       = 0xebc
 	IMAGE_FILE_MACHINE_I386      = 0x14c