*/*: Fix build with llvm16 on 13.2-STABLE

As like as HEAD(14.0-RELEASE) llvm16 was merged in base for 13.2-STABLE
with the OSVERSION 1302507.

- Utilize USE_CXXSTD=c++14 or similar solution where applicable
- Update conditionals to addtionally check for OSVERSION greater than
  1302507 and less than 1400000

Approved by:	portmgr (blanket)
Sponsored by:	The FreeBSD Foundation