libstdc++: construct bitset from string_view (P2697) [PR119742]

Add a bitset constructor from string_view, per P2697. Fix existing
tests that would fail to detect incorrect exception behavior.

Argument checks that result in exceptions guarded by "#if HOSTED"
are made unguarded because the functions called to throw just call
terminate() in free-standing builds. Improve readability in Doxygen
comments. Generalize a private member argument-checking function
to work with string and string_view without mentioning either,
obviating need for guards.

The version.h symbol is not "hosted" because string_view, though
not specified to be available in free-standing builds, is defined
there and the feature is useful there.

libstdc++-v3/ChangeLog:
	PR libstdc++/119742
	* include/bits/version.def: Add preprocessor symbol.
	* include/bits/version.h: Add preprocessor symbol.
	* include/std/bitset: Add constructor.
	* testsuite/20_util/bitset/cons/1.cc: Fix.
	* testsuite/20_util/bitset/cons/6282.cc: Fix.
	* testsuite/20_util/bitset/cons/string_view.cc: Test new ctor.
	* testsuite/20_util/bitset/cons/string_view_wide.cc: Test new ctor.

0 files changed, 0 insertions, 0 deletions