Fix sys/socket.h namespace issues from sys/uio.h inclusion (bug 21426).

sys/socket.h includes sys/uio.h to get the definition of the iovec
structure.

POSIX allows sys/socket.h to make all sys/uio.h symbols visible.
However, all of sys/uio.h is XSI-shaded, so for non-XSI POSIX this
results in conformtest failures (for sys/socket.h and other headers
that include it):

    Namespace violation: "UIO_MAXIOV"
    Namespace violation: "readv"
    Namespace violation: "writev"

Now, there is some ambiguity in POSIX about what namespace
reservations apply in this case - see
http://austingroupbugs.net/view.php?id=1127 - but glibc convention
would still avoid declaring readv and writev, for example, for feature
test macros that don't include them (if only headers from the relevant
standard are included), even if such declarations are permitted, so
there is a bug here according to glibc conventions.

This patch moves the struct iovec definition to a new
bits/types/struct_iovec.h header and includes that from sys/socket.h
instead of including the whole of sys/uio.h.  This fixes the namespace
issue; however, three files in glibc that were relying on the implicit
inclusion needed to be updated to include sys/uio.h explicitly.  So
there is a question of whether sys/socket.h should continue to include
sys/uio.h under some conditions, such as __USE_XOPEN or __USE_MISC or
__USE_XOPEN || __USE_MISC, for greater compatibility with code that
(wrongly) expects this optional inclusion to be present there.  (I
think the three affected files in glibc should still have explicit
sys/uio.h inclusions added in any case, however.)

Tested for x86_64.

	[BZ #21426]
	* misc/bits/types/struct_iovec.h: New file.
	* misc/Makefile (headers): Add bits/types/struct_iovec.h.
	* include/bits/types/struct_iovec.h: New file.
	* bits/uio.h (struct iovec): Replace by inclusion of
	<bits/types/struct_iovec.h>.
	* sysdeps/unix/sysv/linux/bits/uio.h (struct iovec): Likewise.
	* socket/sys/socket.h: Include <bits/types/struct_iovec.h> instead
	of <sys/uio.h>.
	* nptl/tst-cancel4.c: Include <sys/uio.h>
	* posix/test-errno.c: Likewise.
	* support/resolv_test.c: Likewise.
	* conform/Makefile (test-xfail-POSIX2008/arpa/inet.h/conform):
	Remove.
	(test-xfail-POSIX2008/netdb.h/conform): Likewise.
	(test-xfail-POSIX2008/netinet/in.h/conform): Likewise.
	(test-xfail-POSIX2008/sys/socket.h/conform): Likewise.

1 files changed, 1 insertions, 0 deletions

diff --git a/support/resolv_test.c b/support/resolv_test.c
index 5c5a46353d..050cd7154b 100644
--- a/support/resolv_test.c
+++ b/support/resolv_test.c
@@ -33,6 +33,7 @@
 #include <support/xsocket.h>
 #include <support/xthread.h>
 #include <support/xunistd.h>
+#include <sys/uio.h>
 #include <unistd.h>
 
 /* Response builder.  */