[PATCH] [lld] [mach-o] Support -l and -syslibroot options

[kledzik at apple.com]

I'd change SmallString<128> to SmallString<256> because most sdk usages are buried inside Xcode.app and start at 120 chars.

Otherwise, LGTM

================
Comment at: lib/Driver/DarwinLdOptions.td:72-73
@@ -71,1 +71,4 @@
         Group<grp_libs>;
+def syslibroot : Separate<["-"], "syslibroot">,
+        HelpText<"Add prefix to all system library search paths">,
+        Group<grp_libs>;
----------------
A better help message would be "path to SDK"

================
Comment at: lib/Driver/DarwinLdOptions.td:78
@@ -72,1 +77,3 @@
+def l : Joined<["-"], "l">,
+        HelpText<"Root name of library to searchf for">;
 
----------------
HelpText<"Base name of library searched for in -L directories">;

http://reviews.llvm.org/D4409