For the various lang/python* ports, improve the __FreeBSD_version
check in pyport.h for working around a very old ctype issue.

If the workaround for this issue is enabled, pyport.h redefines
toupper() and some other ctype macros, and this wreaks havoc when
including newer libc++ headers (or any other system header which tries
to declare those functions).

Approved by: portmgr (antoine)
PR: 208486
MFH: 2016Q2