More FreeBSD compatiblity

[Sebastian Huber]

With this patch set we are able to build the FreeBSD 9.3 network stack (about
800 user and kernel space source files) on RTEMS directly using

  <machine/endian.h>
  <sys/_stdint.h>
  <sys/time.h>
  <sys/_types.h>
  <sys/types.h>

from Newlib.