posix: Set p{read,write}v2 to return ENOTSUP (BZ#21780)

Different than other architectures hppa-linux-gnu define different values
for ENOTSUP and EOPNOTSUPP, where the later is a Linux specific one.
This leads to tst-preadwritev{64}v2 tests failures:

$ ./testrun.sh misc/tst-preadvwritev2
error: tst-preadvwritev2-common.c:35: preadv2 failure did not set errno to ENOTSUP (223)
error: 1 test failures

The straightforward fix is to return the POSIX defined ENOTSUP on all
p{read,write}v{64}v2 implementations instead of Linux specific one.

Checked on x86_64-linux-gnu and the tst-preadwritev{64}v2 on
hppa-linux-gnu (although due the installed kernel on my testing system
the pwritev{64}v2 with an invalid flag still fails due a known kernel
issue [1]).

	[BZ #21780]
	* sysdeps/posix/preadv2.c (preadv2): Use ENOTSUP instead of
	EOPNOTSUPP.
	* sysdeps/posix/preadv64v2.c (preadv64v2): Likewise.
	* sysdeps/posix/pwritev2.c (pwritev2): Likewise.
	* sysdeps/posix/pwritev64v2.c (pwritev64v2): Likewise.
	* sysdeps/unix/sysv/linux/preadv2.c (preadv2): Likewise.
	* sysdeps/unix/sysv/linux/preadv64v2.c (preadv64v2): Likewise.
	* sysdeps/unix/sysv/linux/pwritev2.c (pwritev2): Likewise.
	* sysdeps/unix/sysv/linux/pwritev64v2.c (pwritev64v2): Likewise.

[1] https://sourceware.org/ml/libc-alpha/2017-06/msg00726.html

Cherry-pick of 852d63120783fae5bf85a067320dc4ba1ed59f11

1 files changed, 2 insertions, 2 deletions

diff --git a/sysdeps/unix/sysv/linux/preadv2.c b/sysdeps/unix/sysv/linux/preadv2.c
index 11fe85eaa8..137e2dd791 100644
--- a/sysdeps/unix/sysv/linux/preadv2.c
+++ b/sysdeps/unix/sysv/linux/preadv2.c
@@ -32,7 +32,7 @@ preadv2 (int fd, const struct iovec *vector, int count, off_t offset,
 # ifdef __NR_preadv2
   ssize_t result = SYSCALL_CANCEL (preadv2, fd, vector, count,
 				   LO_HI_LONG (offset), flags);
-  if (result >= 0 || errno != ENOSYS)
+  if (result >= 0)
     return result;
 # endif
   /* Trying to emulate the preadv2 syscall flags is troublesome:
@@ -46,7 +46,7 @@ preadv2 (int fd, const struct iovec *vector, int count, off_t offset,
 
   if (flags != 0)
     {
-      __set_errno (EOPNOTSUPP);
+      __set_errno (ENOTSUP);
       return -1;
     }
   return preadv (fd, vector, count, offset);