linux: Implement pipe in terms of __NR_pipe2

The syscall pipe2 was added in linux 2.6.27 and glibc requires linux
3.2.0.  The patch removes the arch-specific implementation for alpha,
ia64, mips, sh, and sparc which requires a different kernel ABI
than the usual one.

Checked on x86_64-linux-gnu and with a build for the affected ABIs.

sysdeps/unix/sysv/linux/pipe.c

@@ -0,0 +1,32 @@
+/* Create create pipe.  Linux generic version.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <unistd.h>
+#include <sysdep.h>
+
+/* Create a one-way communication channel (__pipe).
+   If successful, two file descriptors are stored in PIPEDES;
+   bytes written on PIPEDES[1] can be read from PIPEDES[0].
+   Returns 0 if successful, -1 if not.  */
+int
+__pipe (int __pipedes[2])
+{
+  return INLINE_SYSCALL_CALL (pipe2, (int *) __pipedes, 0);
+}
+libc_hidden_def (__pipe)
+weak_alias (__pipe, pipe)