[glibc] Revert "hppa: Drop 16-byte pthread lock alignment"

[John David Anglin <danglin@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=500054974667be3153ed760152ea0153df33c3d0

commit 500054974667be3153ed760152ea0153df33c3d0
Author: John David Anglin <danglin@gcc.gnu.org>
Date:   Thu Jul 6 15:47:50 2023 +0000

    Revert "hppa: Drop 16-byte pthread lock alignment"
    
    This change reverts commits c4468cd3995b4236ea886901109b194641132b08
    and ab991a3d1b401ded6bd4f027352da8262b021a11.

Diff:
---
 sysdeps/hppa/nptl/bits/pthreadtypes-arch.h |  2 +-
 sysdeps/hppa/nptl/bits/struct_rwlock.h     | 10 ++--------
 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/sysdeps/hppa/nptl/bits/pthreadtypes-arch.h b/sysdeps/hppa/nptl/bits/pthreadtypes-arch.h
index c1a46d66d0..999195c5b0 100644
--- a/sysdeps/hppa/nptl/bits/pthreadtypes-arch.h
+++ b/sysdeps/hppa/nptl/bits/pthreadtypes-arch.h
@@ -40,7 +40,7 @@
 #define __SIZEOF_PTHREAD_RWLOCK_T 64
 #define __SIZEOF_PTHREAD_RWLOCKATTR_T 8
 
-#define __LOCK_ALIGNMENT
+#define __LOCK_ALIGNMENT __attribute__ ((__aligned__(16)))
 #define __ONCE_ALIGNMENT
 
 #endif	/* bits/pthreadtypes.h */
diff --git a/sysdeps/hppa/nptl/bits/struct_rwlock.h b/sysdeps/hppa/nptl/bits/struct_rwlock.h
index f91460b7f8..e83b4aab52 100644
--- a/sysdeps/hppa/nptl/bits/struct_rwlock.h
+++ b/sysdeps/hppa/nptl/bits/struct_rwlock.h
@@ -25,14 +25,8 @@ struct __pthread_rwlock_arch_t
   /* In the old Linuxthreads pthread_rwlock_t, this is the
      start of the 4-word 16-byte aligned lock structure. The
      next four words are all set to 1 by the Linuxthreads
-     PTHREAD_RWLOCK_INITIALIZER. We ignore them in NPTL.
-
-     The 16-byte aligned lock structure is not needed for NPTL.
-     It causes some package builds to fail (e.g., protobuf) and
-     issues with dynamic memory allocation in C++ versions prior
-     to C++17. Removing it allows for more efficient allocators
-     and better compatibility with other architectures.  */
-  int __compat_padding[4];
+     PTHREAD_RWLOCK_INITIALIZER. We ignore them in NPTL.  */
+  int __compat_padding[4] __attribute__ ((__aligned__(16)));
   unsigned int __readers;
   unsigned int __writers;
   unsigned int __wrphase_futex;