Check for EINTR in poll$nt()

This is a bandaid that lets CTRL-C work in daemons until a better
solution for signals on Windows can be implemented.

libc/calls/g_sighandrvas.c

@@ -18,4 +18,4 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/internal.h"
 
-hidden int g_sighandrvas[NSIG];
+unsigned __sighandrvas[NSIG];