lang/gnat12: install in a separate directory with its own gcc
Gnat runs along with a gcc compiled with Ada, but we don’t want neither
modify lang/gcc12 nor conflict with it. Therefore we have to install it
in a separate directory.
lang/gnat12: adding GNAT from Gcc-12
This Ada compiler is built from Gcc-12, with help from Stephane Carrez
The first time it uses lang/gcc6-aux as a bootstrap, but it can produce
a bootstrap for the next time, either for this version or for the next
Yet to be done:
- plug it into Mk/Uses/ada.mk
- build more bootstrapping assets
(ATM they exist only for amd64 on FreeBSD 13 and 14)
- add a test target
- try to cross-compile for more platforms?