Fix network headers stdint.h namespace (bug 21455).

Fix network headers stdint.h namespace (bug 21455).

conform/ namespace tests of arpa/inet.h, netdb.h and netinet/in.h fail
for UNIX98 and XPG42 because of inclusion of stdint.h, which defines
macros not permitted in those headers for those standards.  UNIX98
allows them to include inttypes.h, but (predating C99) has restricted
inttypes.h contents (not yet tested in the conform/ tests) not
including those macros; XPG4.2 has no such permission and no
inttypes.h / stdint.h at all.

This patch rearranges the headers to avoid this issue.  intN_t
definitions move to bits/stdint-intn.h, and uintN_t definitions to
bits/stdint-uintn.h.  (These are not bits/types/ headers because they
each define four types.  They are separate rather than just a single
header because sys/types.h defines intN_t but u_intN_t rather than
uintN_t - and while sys/types.h could define uintN_t because of the
POSIX reservation of *_t, existing practice there is largely to
condition types on appropriate feature test macros, and indeed there
is at least one open bug report (14553) about a type that's not
so-conditioned, so maybe types there should actually have conditions
added where appropriate.)  The affected network headers are then made
to include bits/stdint-uintn.h instead of stdint.h.  This allows six
XFAILs to be removed.

This doesn't do anything about inttypes.h defining more than it should
for UNIX98, but we don't have conformtest expectations for that case
at present (and my inclination is that a fix for that should be as
local as possible - affecting only inttypes.h, not stdint.h, only for
the case of __USE_UNIX98 && !__USE_ISOC99).

Tested for x86_64.

	[BZ #21455]
	* bits/stdint-intn.h: New file.
	* bits/stdint-uintn.h: Likewise.
	* stdlib/Makefile (headers): Add bits/stdint-intn.h and
	bits/stdint-uintn.h.
	* inet/netinet/in.h: Include <bits/stdint-uintn.h> instead of
	<stdint.h>.
	* posix/sys/types.h: Include <bits/stdint-intn.h>.
	(__int8_t_defined): Do not define here.
	(int8_t): Likewise.
	(int16_t): Likewise.
	(int32_t): Likewise.
	(int64_t): Likewise.
	[__GNUC_PREREQ (2, 7)] (__intN_t): Likewise.
	* resolv/netdb.h: Include <bits/stdint-uintn.h> instead of
	<stdint.h>.
	* include/netdb.h [_ISOMAC]: Do not include <stdint.h>.
	* sysdeps/generic/stdint.h: Include <bits/stdint-intn.h> and
	<bits/stdint-uintn.h>.
	(int8_t): Do not define here.
	(int16_t): Likewise.
	(int32_t): Likewise.
	(int64_t): Likewise.
	(uint8_t): Likewise.
	(uint16_t): Likewise.
	(uint32_t): Likewise.
	(uint64_t): Likewise.
	* conform/Makefile (test-xfail-XPG42/arpa/inet.h/conform): Remove
	variable.
	(test-xfail-XPG42/netdb.h/conform): Likewise.
	(test-xfail-XPG42/netinet/in.h/conform): Likewise.
	(test-xfail-UNIX98/arpa/inet.h/conform): Likewise.
	(test-xfail-UNIX98/netdb.h/conform): Likewise.
	(test-xfail-UNIX98/netinet/in.h/conform): Likewise.