a) The BUILD_ADA must be YES (strictly capitalized) for the
pre-configure target to work, which is inconsistent.
b) For me (using ALT_GCC), the directory .work/.gcc was not
present at pre-configure time, which made some "cd" fail.
2) Makefile cleanup as recommended by Lubomir.
3) pkglint cleanup
4) Increment PKGREVISION