lang/gcc14: Add port

GCC, the GNU Compiler Collection, supports a number of languages.
This port installs the C, C++, and Fortran front ends as gcc14,
g++14, and gfortran14, respectively.

This is the first release from the GCC 14 series.
It largely is a copy of lang/gcc14-devel, with release-specific
modifications from lang/gcc13.

Common issues that could happen when porting code to GCC 14:
https://gcc.gnu.org/gcc-14/porting_to.html

Changes: https://gcc.gnu.org/gcc-14/changes.html