c/numeric/fenv/FE exceptions

All these macro constants (except fe_all_except) expand to integer constant expressions that are distinct powers of 2, which uniquely identify all supported floating-point exceptions. Each macro is only defined if it is supported.

The macro constant fe_all_except, which expands to the bitwise OR of all other, is always defined and is zero if floating-point exceptions are not supported by the implementation.

The implementation may define additional macro constants in to identify additional floating-point exceptions. All such constants begin with followed by at least one uppercase letter.

See math_errhandling for further details.