fsck, checktty, flock: Use more portable includes.

Signed-off-by: Josiah Worcester <josiahw@gmail.com>

fsck/fsck.c

@@ -29,7 +29,7 @@
 
 #include <sys/types.h>
 #include <sys/wait.h>
-#include <sys/signal.h>
+#include <signal.h>
 #include <sys/stat.h>
 #include <sys/file.h>
 #include <fcntl.h>

login-utils/checktty.c

@@ -22,7 +22,10 @@
 #include <malloc.h>
 #include <netdb.h>
 #include <sys/syslog.h>
+#include <sys/socket.h>
 #include <ctype.h>
+#include <limits.h>
+#include <netinet/in.h>
 #include "nls.h"
 
 #include <sys/sysmacros.h>

sys-utils/flock.c

@@ -39,6 +39,8 @@
 #include <sys/file.h>
 #include <sys/time.h>
 #include <sys/wait.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 
 #include "nls.h"