Use _MSC_VER to check for existence of isinf/isnan.
Use _MSC_VER to check for existence of isinf/isnan.

Let's use this variant of the check that's also used in the main PostgreSQL
sources. It has been shown to work, so should be more robust.

Per suggestions from Michael Paquier and Tom Lane.

gavioto/psqlodbc,gavioto/psqlodbc,gavioto/psqlodbc