libstdc++: Fix uses of non-reserved names in headers

libstdc++: Fix uses of non-reserved names in headers

The non-reserved names 'val' and 'dest' were being used in our headers
but haven't been added to the 17_intro/names.cc test. That's because
they are used by <asm-generic/posix_types.h> and <netinet/tcp.h>
respecitvely on glibc-based systems.

libstdc++-v3/ChangeLog:

	* include/bits/fs_ops.h (create_directory): Use reserved name
	for parameter.
	* include/bits/ranges_algo.h (__contains_subrange_fn):
	Likewise.
	* include/bits/regex_automaton.h (_State_base::_M_print):
	Likewise.
	* include/bits/regex_automaton.tcc(_State_base::_M_print):
	Likewise.
	* include/bits/regex_scanner.tcc(_Scanner::_M_print): Likewise.
	* include/experimental/bits/fs_ops.h (create_directory):
	Likewise.
	* include/std/mutex (timed_mutex::_M_clocklock): Likewise.
	(recursive_timed_mutex:_M_clocklock): Likewise.
	* include/std/tuple (basic_common_reference): Likewise.
	* libsupc++/cxxabi_init_exception.h
	(__cxa_init_primary_exception): Likewise.
	* testsuite/17_intro/names.cc: Add checks.