isnan workaround OS detection missing NetBSD, DragonFly, Sun nuance

[gdt]

On a number of systems, there is an issue with cmath.h and isnan visibility. include/geos/platform.h.in has a test for apple. pkgsrc has a patch to extend this test for NetBSD and DragonFly, and to split sun into sunpro and gcc. Absent objections, this patch should be applied to geos proper.

It's hard to tell the significant of this; geos fails to build on these platforms without this patch, but packaging currently works around it.

The attached patch is available under a modified BSD license, and may well not be adequately creative to be subject to copyright.

(There should be a longer-term fix to determine what kind of treatment isnan needs via a configure test, rather than OS ifdefs, but this ticket is about the simpler task of extending the kludge.)

[robe]

applied for 3.4 branch at r3902

still need to apply to 3.5 branch.

[robe]

oops r3902 was for 3.5 (BTW I get 4 failures on 3.5 (nothing to do with this ticket since I got the same failures before)

r3903 is for 3.4 branch