Make some more fixes

This change deletes mkfifo() so that GNU Make on Windows will work in
parallel mode using its pipe-based implementation. There's an example
called greenbean2 now, which shows how to build a scalable web server
for Windows with 10k+ threads. The accuracy of clock_nanosleep is now
significantly improved on Linux.

examples/greenbean.c

@@ -304,7 +304,7 @@ int main(int argc, char *argv[]) {
   // print cpu registers and backtrace on crash
   // note that pledge'll makes backtraces worse
   // you can press ctrl+\ to trigger backtraces
-  ShowCrashReports();
+  // ShowCrashReports();
 
   // listen for ctrl-c, terminal close, and kill
   struct sigaction sa = {.sa_handler = OnTerm};