m68k: don't expect PLT reference to __tls_get_addr
Update minimal required bunutils version to 2.22
PowerPC: Add the low level infrastructure for pthreads

This patch adds support for lock elision using ISA 2.07 hardware
transactional memory instructions for pthread_mutex primitives.
Similar to s390 version, the for elision logic defined in
'force-elision.h' is only enabled if ENABLE_LOCK_ELISION is defined.

Also, the lock elision code should be able to be built even with
a compiler that does not provide HTM support with builtins.
However I have noted the performance is sub-optimal due scheduling
pressures.
PowerPC: Add adaptive elision to rwlocks

This patch adds support for lock elision using ISA 2.07 hardware
transactional memory for rwlocks.  The logic is similar to the
one presented in pthread_mutex lock elision.
PowerPC: abort transaction in syscalls

Linux kernel powerpc documentation states issuing a syscall inside a
transaction is not recommended and may lead to undefined behavior. It
also states syscalls does not abort transactoin neither they run in
transactional state.

To avoid side-effects being visible outside transactions, GLIBC with
lock elision enable issues a transaction abort instruction just before all
syscalls if hardware supports hardware transactions.