LibC: Bump FD_SETSIZE to 1024

64 was cutting it pretty close, especially now as we start using file
descriptor passing more and more.

This (1024) matches many other systems, and if we need more there's
always sys$poll().

Userland/Libraries/LibC/fd_set.h

@@ -26,7 +26,7 @@
 
 #pragma once
 
-#define FD_SETSIZE 64
+#define FD_SETSIZE 1024
 #define FD_ZERO(set) memset((set), 0, sizeof(fd_set));
 #define FD_CLR(fd, set) ((set)->bits[(fd / 8)] &= ~(1 << (fd) % 8))
 #define FD_SET(fd, set) ((set)->bits[(fd / 8)] |= (1 << (fd) % 8))