[config] Extend auto::infnan probe to other --floatval #1146

also check the real output for isnan and isinf.
maybe we should also check for NAN != NAN
math dynop: Fix cmod_p_p_n* for NaN and Inf #1147

Return a string in this case.
[core] Fix floor, ceil and complex, integer math ops for NaN/Inf

Closes #422: Rounding Inf and NaN (in fact all math ops with floats),
throw EXCEPTION_LOSSY_CONVERSION, "Invalid number" when Nan/Inf => Int
otherwise returns a String PMC or if Float passes Nan/Inf through.

Closes GH #1147, no remaining NaN/Inf TODO tests.
[test] fix t/pmc/integer.t for long double

GH #828
[codingstd] fix hard tabs in math.ops