getflags: use shell quoting

R=rsc
CC=codebot
http://codereview.appspot.com/2065042

src/cmd/getflags.c

@@ -43,6 +43,7 @@ main(int argc, char *argv[])
 	int i, n;
 	Fmt fmt;
 	
+	doquote = needsrcquote;	
 	quotefmtinstall();
 	argv0 = argv[0];	/* for sysfatal */