* All files with FSF copyright notices: Update copyright dates
	using scripts/update-copyrights.
	* locale/programs/charmap-kw.h: Regenerated.
	* locale/programs/locfile-kw.h: Likewise.

POSIX requires that dlclose() and exit() be thread safe, therefore
you can have one thread in the middle of dlclose() and another thread
executing exit() without causing any undefined behaviour on the part
of the implementation.

The existing implementation had a flaw that exit() exit handler processing
did not consider a concurrent dlclose() and would not mark already run
exit handlers using the ef_free flavour. The consequence of this is that
a concurrent exit() with dlclose() will run all the exit handlers that
dlclose() had not yet run, but then will block on the loader lock. The
concurrent dlclose() will continue to run all the exit handlers again
(twice) in violation of the Itanium C++ ABI requirements for __cxa_atexit().

This commit fixes this by having exit() mark all handlers with ef_free to
ensure that concurrent dlclose() won't re-run registered exit handlers that
have already run.

In C++11 18.5.12 says "Objects shall not be destroyed as a
result of calling quick_exit." In C11 quick_exit is silent
about thread object destruction. Therefore to make glibc
C++ compliant we do not call any thread local destructors.
A new regression test verifies the fix.

I will note that C++11 18.5.3 makes it clear that C++
defines additional requirements for _Exit() to prevent it
from executing destructors.

Given that the point of _Exit() is to terminate the process
immediately it makes sense the C and C++ should line up
and avoid calling destructors.

No failures. New regtest passes.

This feature is specifically for the C++ compiler to offload calling
thread_local object destructors on thread program exit, to glibc.
This is to overcome the possible complication of destructors of
thread_local objects getting called after the DSO in which they're
defined is unloaded by the dynamic linker.  The DSO is marked as
'unloadable' if it has a constructed thread_local object and marked as
'unloadable' again when all the constructed thread_local objects
defined in it are destroyed.