Various additions and fixes.

src/lib9/rfork.c

@@ -0,0 +1,20 @@
+#define NOPLAN9DEFINES
+#include <lib9.h>
+
+int
+p9rfork(int flags)
+{
+	if(flags&RFPROC){
+		werrstr("cannot use rfork to fork -- use ffork");
+		return -1;
+	}
+	if(flags&RFNOTEG){
+		setpgrp(0, 0);
+		flags &= ~RFNOTEG;
+	}
+	if(flags){
+		werrstr("unknown flags %08ux in rfork", flags);
+		return -1;
+	}
+	return 0;
+}