kbuild: Use POSIX headers for ntoh functions

From: Benno <benjl@cse.unsw.edu.au>
When compiling Linux on Mac OSX I had trouble with scripts/sumversion.c.
It includes <netinet/in.h> to obtain to definitions of htonl and ntohl.

On Mac OSX these are found in <arpa/inet.h>. After checking the POSIX
specification it appears that this is the correct place to get
the definitons for these functions.

(http://www.opengroup.org/onlinepubs/009695399/functions/htonl.html)

Using this header also appears to work on Linux (at least with
Glibc-2.3.2).

It seems clearer to me to go with the POSIX standard than implementing
#if __APPLE__ style macros, but if such an approach is preferred I can
supply patches for that instead.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

scripts/basic/fixdep.c

@@ -104,7 +104,7 @@
 #include <stdio.h>
 #include <limits.h>
 #include <ctype.h>
-#include <netinet/in.h>
+#include <arpa/inet.h>
 
 #define INT_CONF ntohl(0x434f4e46)
 #define INT_ONFI ntohl(0x4f4e4649)

scripts/mod/sumversion.c

-#include <netinet/in.h>
+#include <arpa/inet.h>
 #include <stdint.h>
 #include <ctype.h>
 #include <errno.h>