devdraw: add multitouch code from Paul Lalonde

Various tweaks to avoid breaking standard mice,
but probably needs tweaks to work with multitouch
mice again.  Still, it's a start.

R=rsc
CC=plalonde, r
http://codereview.appspot.com/181124

src/cmd/devdraw/mkwsysrules.sh

@@ -47,7 +47,11 @@ if [ $WSYSTYPE = x11 ]; then
 	XO=`ls x11-*.c 2>/dev/null | sed 's/\.c$/.o/'`
 	echo 'WSYSOFILES=$WSYSOFILES '$XO
 elif [ $WSYSTYPE = osx ]; then
-	echo 'WSYSOFILES=$WSYSOFILES osx-screen.o osx-draw.o osx-srv.o'
+	if [ -d /System/Library/PrivateFrameworks/MultitouchSupport.framework ]; then
+		echo 'CFLAGS=$CFLAGS -DMULTITOUCH'
+		echo 'LDFLAGS=$LDFLAGS -F/System/Library/PrivateFrameworks'
+	fi
+	echo 'WSYSOFILES=$WSYSOFILES osx-screen-carbon-objc.o osx-draw.o osx-srv.o'
 elif [ $WSYSTYPE = nowsys ]; then
 	echo 'WSYSOFILES=nowsys.o'
 fi