Various additions and fixes.

src/lib9/ffork-pthread.c

@@ -0,0 +1,26 @@
+#include <lib9.h>
+#include <pthread.h>
+
+extern int __isthreaded;
+int
+ffork(int flags, void(*fn)(void*), void *arg)
+{
+	void *p;
+	pthread_t tid;
+
+	if(flags != (RFMEM|RFNOWAIT)){
+		werrstr("ffork unsupported");
+		return -1;
+	}
+
+	if(pthread_create(&tid, NULL, (void*(*)(void*))fn, arg) < 0)
+		return -1;
+	return (int)tid;
+}
+
+int
+getfforkid(void)
+{
+	return (int)pthread_self();
+}
+