The fix consists of three commits backported from 10.3:

1) Cleanup isnan() portability checks

(cherry picked from commit 7ffd7fe9)

2) Cleanup isinf() portability checks

Original problem reported by Wlad: re-compilation of 10.3 on top of 10.2
build would cache undefined HAVE_ISINF from 10.2, whereas it is expected
to be 1 in 10.3.

std::isinf() seem to be available on all supported platforms.
(cherry picked from commit bc469a0b)

3) Use std::isfinite in C++ code

This is addition to parent revision fixing build failures.

(cherry picked from commit 54999f4e)