debug/macho: add comments for ambiguious LoadCommand

While LoadCmdDylib represents LC_LOAD_DYLIB,
LoadCmdDylinker represents LC_ID_DYLINKER.
This is confusing because there is another command called LC_LOAD_DYLINKER.
LC_ID_DYLINKER is not included in normal binary, it is only used for
/usr/lib/dyld as far as I know. So, perhaps this is a mistake.

Change-Id: I6ea61664a26998962742914af5688e094a233541
Reviewed-on: https://go-review.googlesource.com/56330Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/debug/macho/macho.go

@@ -84,8 +84,8 @@ const (
 	LoadCmdThread     LoadCmd = 0x4
 	LoadCmdUnixThread LoadCmd = 0x5 // thread+stack
 	LoadCmdDysymtab   LoadCmd = 0xb
-	LoadCmdDylib      LoadCmd = 0xc
-	LoadCmdDylinker   LoadCmd = 0xf
+	LoadCmdDylib      LoadCmd = 0xc // load dylib command
+	LoadCmdDylinker   LoadCmd = 0xf // id dylinker command (not load dylinker command)
 	LoadCmdSegment64  LoadCmd = 0x19
 )