GCC 6.1 was released this week. The Ada Framework in FreeBSD ports has
been based on GCC 5.3 GNAT although GCC 6.x has been supported for awhile
via the ADA_DEFAULT option in make.conf.
Now that GCC 6 has been officially released, switch to it by default.
People can maintain the old foundation by putting "ADA_DEFAULT=5" in
/etc/make.conf.
Libraries built by one GNAT are unusable by another, so almost every Ada
port has been bumped as a result. Noticable exceptions are dns/ironsides
which fails to build on gcc6 (thus USES=ada:5 is set) and cad/ghdl which
needs additional testing as it may require gcc5 on FreeBSD (DragonFly
uses the LLVM backend only).