This squashes two commits, r11-674 and r11-1401.

	PR libstdc++/95282
	* include/bits/atomic_base.h (__atomic_impl::load): Add
	const-qualifier to parameter so that _Tp is deduced as the
	non-const type, and use _Val to get the unqualified type.
	(__atomic_impl::exchange): Use the _Val alias to remove
	volatile from the reinterpret_cast result type.
	* testsuite/29_atomics/atomic_float/95282.cc: New test.

(cherry picked from commit e40b11a91cb345db1324c3cb8f75b01e28056693)