Fix perror fileno namespace (bug 17633).
perror, an ISO C function, uses fileno, which is not an ISO C
function. This patch makes it use __fileno instead. (The nearby call
to fdopen is not a problem because that's #defined to _IO_new_fdopen.)
Tested for x86_64 (testsuite, and that installed stripped shared
libraries are unchanged by this patch).
[BZ #17633]
* stdio-common/perror.c (perror): Call __fileno instead of fileno.
* conform/Makefile (test-xfail-ISO/stdio.h/linknamespace): Remove
variable.
(test-xfail-ISO99/stdio.h/linknamespace): Likewise.
(test-xfail-ISO11/stdio.h/linknamespace): Likewise.