libstdc++: Add noexcept to std::begin etc as per LWG 2280 and 3537
This implements the proposed changes for LWG 3537 (which we're allowed
to do as an extension whatever the outcome of the issue). I noticed we
didn't implement LWG 2280 completely, as the std::begin and std::end
overloads for arrays were not noexcept.
libstdc++-v3/ChangeLog:
* include/bits/range_access.h (begin(T (&)[N]), end(T (&)[N])):
Add missing 'noexcept' as per LWG 2280.
(rbegin(T (&)[N]), rend(T (&)[N]), rbegin(initializer_list<T>))
(rend(initializer_list<T>)): Add 'noexcept' as per LWG 3537.
* testsuite/24_iterators/range_access/range_access.cc: Check for
expected noexcept specifiers. Check result types of generic
std::begin and std::end overloads.
* testsuite/24_iterators/range_access/range_access_cpp14.cc:
Check for expected noexcept specifiers.
* testsuite/24_iterators/range_access/range_access_cpp17.cc:
Likewise.