1) Replace custom tarball with Adacore's GPL 2012 release
2) Update license to GPLv3
3) Remove lang/gnat-aux dependency
4) USE_LANGUAGES+= ada (invokes lang/gcc-aux dependency)
5) Update buildlink3.mk to require GPL 2012 version
6) Restore use of pkgsrc wrappers
7) Add Library_Option "-R" support which ignores all automatically
generated rpaths* which point to the WRKOBJDIR. DESTDIR isn't
supported by GPRBuild, so this rpath disabling is necessary to
avoid references to work directories.
* gcc and adalib rpaths are excluded with -R option.
8) This Library_Option "-R" matches the same modification added to
lang/gcc-aux and lang/gnat-aux's project handler.
9) This modification is required to fix www/aws rpath issues which
appears with recent changes to PKG_DEVELOPER=yes checks.
