devdraw: map X11 dead_diaresis to double quote

R=rsc
CC=plan9port.codebot
http://codereview.appspot.com/6690049

CONTRIBUTORS

@@ -11,6 +11,7 @@ Anthony Martin <ality@pbrane.org>
 Anthony Sorace <a@9srv.net>
 Arvindh Rajesh Tamilmani <art@a-30.net>
 Benjamin Huntsman <BHuntsman@mail2.cu-portland.edu>
+Caio Oliveira <cmarcelo@gmail.com>
 Christopher Brannon <chris@the-brannons.com>
 David du Colombier <0intro@gmail.com>
 David Jeannot <djeannot24@gmail.com>

src/cmd/devdraw/x11-keysym2ucs.c

@@ -843,6 +843,9 @@ long _p9keysym2ucs(KeySym keysym)
 	case 0xfe50: /*dead_grave*/
 		keysym = 0x0060; /*grave*/
 		break;
+	case 0xfe57: /*dead_diaresis*/
+		keysym = 0x0022; /*quotedbl*/
+		break;
 	default:
 		break;
 	}