fenv-exceptions-tracking-c99: Fix test failures on Minix. * m4/fenv-exceptions-tracking.m4 (gl_FENV_EXCEPTIONS_TRACKING): On Minix, set REPLACE_FECLEAREXCEPT and REPLACE_FETESTEXCEPT to 1. * doc/posix-functions/feclearexcept.texi: Mention the Minix bug. * doc/posix-functions/fetestexcept.texi: Likewise.