[PATCH 1/3] nptl: Move pthread_sigmask implementation to libc

[Florian Weimer]

* Adhemerval Zanella via Libc-alpha:

> diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> index a4c31932cb..694efeb1e4 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
> @@ -1447,6 +1447,7 @@ GLIBC_2.17 pthread_self F
>  GLIBC_2.17 pthread_setcancelstate F
>  GLIBC_2.17 pthread_setcanceltype F
>  GLIBC_2.17 pthread_setschedparam F
> +GLIBC_2.17 pthread_sigmask F
>  GLIBC_2.17 ptrace F
>  GLIBC_2.17 ptsname F
>  GLIBC_2.17 ptsname_r F
> diff --git a/sysdeps/unix/sysv/linux/aarch64/libpthread.abilist b/sysdeps/unix/sysv/linux/aarch64/libpthread.abilist
> index d65beba958..48b368acb1 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/libpthread.abilist
> +++ b/sysdeps/unix/sysv/linux/aarch64/libpthread.abilist
> @@ -156,7 +156,6 @@ GLIBC_2.17 pthread_setconcurrency F
>  GLIBC_2.17 pthread_setname_np F
>  GLIBC_2.17 pthread_setschedprio F
>  GLIBC_2.17 pthread_setspecific F
> -GLIBC_2.17 pthread_sigmask F
>  GLIBC_2.17 pthread_sigqueue F
>  GLIBC_2.17 pthread_spin_destroy F
>  GLIBC_2.17 pthread_spin_init F

This change is not fully compatible: Newly-linked programs may incur
lazy binding failures on older glibc versions because pthread_sigmask
is not present in libc.so.6.

In other cases, we have added a compat symbol and a new symbol
version.