nptl: Move pthread_sigmask implementation to libc

This is part of the libpthread removal project:

  <https://sourceware.org/ml/libc-alpha/2019-10/msg00080.html>

A new symbol version is added on libc to force loading failure
instead of lazy binding one for newly binaries with old loaders.

Checked with a build against all affected ABIs.

sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist

@@ -869,6 +869,7 @@ GLIBC_2.0 pthread_self F
 GLIBC_2.0 pthread_setcancelstate F
 GLIBC_2.0 pthread_setcanceltype F
 GLIBC_2.0 pthread_setschedparam F
+GLIBC_2.0 pthread_sigmask F
 GLIBC_2.0 ptrace F
 GLIBC_2.0 putc F
 GLIBC_2.0 putc_unlocked F
@@ -2174,6 +2175,7 @@ GLIBC_2.30 getdents64 F
 GLIBC_2.30 gettid F
 GLIBC_2.30 tgkill F
 GLIBC_2.30 twalk_r F
+GLIBC_2.32 pthread_sigmask F
 GLIBC_2.4 _IO_fprintf F
 GLIBC_2.4 _IO_printf F
 GLIBC_2.4 _IO_sprintf F

sysdeps/unix/sysv/linux/sparc/sparc32/libpthread.abilist

@@ -71,7 +71,6 @@ GLIBC_2.0 pthread_once F
 GLIBC_2.0 pthread_setcancelstate F
 GLIBC_2.0 pthread_setcanceltype F
 GLIBC_2.0 pthread_setspecific F
-GLIBC_2.0 pthread_sigmask F
 GLIBC_2.0 pthread_testcancel F
 GLIBC_2.0 raise F
 GLIBC_2.0 read F

sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist

@@ -1321,6 +1321,7 @@ GLIBC_2.2 pthread_self F
 GLIBC_2.2 pthread_setcancelstate F
 GLIBC_2.2 pthread_setcanceltype F
 GLIBC_2.2 pthread_setschedparam F
+GLIBC_2.2 pthread_sigmask F
 GLIBC_2.2 ptrace F
 GLIBC_2.2 ptsname F
 GLIBC_2.2 ptsname_r F
@@ -2101,6 +2102,7 @@ GLIBC_2.30 getdents64 F
 GLIBC_2.30 gettid F
 GLIBC_2.30 tgkill F
 GLIBC_2.30 twalk_r F
+GLIBC_2.32 pthread_sigmask F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
 GLIBC_2.4 __fgets_unlocked_chk F

sysdeps/unix/sysv/linux/sparc/sparc64/libpthread.abilist

@@ -136,7 +136,6 @@ GLIBC_2.2 pthread_setcancelstate F
 GLIBC_2.2 pthread_setcanceltype F
 GLIBC_2.2 pthread_setconcurrency F
 GLIBC_2.2 pthread_setspecific F
-GLIBC_2.2 pthread_sigmask F
 GLIBC_2.2 pthread_spin_destroy F
 GLIBC_2.2 pthread_spin_init F
 GLIBC_2.2 pthread_spin_lock F