linux: Add prlimit64 C implementation

The LFS prlimit64 requires a arch-specific implementation in
syscalls.list.  Instead add a generic one that handles the
required symbol alias for __RLIM_T_MATCHES_RLIM64_T.

HPPA is the only outlier which requires a different default
symbol.

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

sysdeps/unix/sysv/linux/prlimit64.c

@@ -0,0 +1,39 @@
+/* Get/set resource limits.  Linux specific syscall.
+   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/>.  */
+
+#define prlimit __redirect_prlimit
+#include <sys/resource.h>
+#undef prlimit
+#include <sysdep.h>
+
+int
+__prlimit64 (pid_t pid, enum __rlimit_resource resource,
+	     const struct rlimit64 *new_rlimit, struct rlimit64 *old_rlimit)
+{
+  return INLINE_SYSCALL_CALL (prlimit64, pid, resource, new_rlimit,
+			      old_rlimit);
+}
+#ifdef VERSION_prlimit64
+# include <shlib-compat.h>
+versioned_symbol (libc, __prlimit64, prlimit64, VERSION_prlimit64);
+#else
+strong_alias (__prlimit64, prlimit64)
+# if __RLIM_T_MATCHES_RLIM64_T
+strong_alias (prlimit64, prlimit)
+# endif
+#endif