[core] isolate use of sys/filio.h

isolate use of sys/filio.h to fdevent_ioctl_fionread()
(illumos (OpenIndiana) defines FIONREAD in sys/filio.h)

src/connections.c

@@ -27,10 +27,6 @@
 #include <errno.h>
 #include <string.h>
 
-#ifdef HAVE_SYS_FILIO_H
-# include <sys/filio.h>
-#endif
-
 #include "sys-socket.h"
 
 #define HTTP_LINGER_TIMEOUT 5

src/mod_ssi.c

@@ -37,10 +37,6 @@
 # include <pwd.h>
 #endif
 
-#ifdef HAVE_SYS_FILIO_H
-# include <sys/filio.h>
-#endif
-
 typedef struct {
 	const array *ssi_extension;
 	const buffer *content_type;