Fighting the good fight.

Move libfmt, libutf into subdirectories of lib9.

Add poll-based socket i/o to libthread, so that we can
avoid using multiple procs when possible, thus removing
dependence on crappy pthreads implementations.

Convert samterm, acme to the single-proc libthread.

Bring libcomplete, acme up-to-date w.r.t. Plan 9 distribution.

src/lib9/nan.c

@@ -1,6 +1,6 @@
 #include <u.h>
 #include <libc.h>
-#include "../libfmt/nan.h"
+#include "fmt/nan.h"
 
 double
 NaN(void)