These tests fail with AIX double double. Use different floating point
values that behave less surprisingly.

libstdc++-v3/ChangeLog:

	PR libstdc++/91153
	PR target/93224
	* testsuite/29_atomics/atomic_float/1.cc: Use different values
	for tests.
	* testsuite/29_atomics/atomic_ref/float.cc: Likewise.

(cherry picked from commit c6f431bba531bac3212b66069cf0f9718edf0132)