The arpa/nameser.h, netinet/ip.h, and resolv.h headers are not crucial
to building LibreSSL. The netinet/ip.h header is used in nc(1) for
optional IPTOS_ features that can be ifdef'd on systems without support.
The endian.h header is the upcoming standard header and should be used
whenever available and correct. The machine/endian.h header is
non-standard and doesn't have to exist on POSIX systems.
Fix the check for getpagesize(3) not forward declaring the function,
such that CFLAGS with -Werror=implicit-function-declaration doesn't
cause the check to fail.
