roundf-ieee tests: More tests. * tests/test-roundf-ieee.c: Include isnanf-nolibm.h, infinity.h, nan.h. (main): Add tests for [MX] shaded specification in POSIX. * modules/roundf-ieee-tests (Files): Add tests/infinity.h, tests/nan.h. (Depends-on): Add isnanf-nolibm.