cleanup: Remove ports depending on expired lang/gcc6-aux

Keep ports-mgmt/synth and dependencies (including lang/gcc6-aux itself)
for now as synth is the only Ada port still maintained and might be
somewhat high-profile.

Removed ports:
archivers/zip-ada
cad/ghdl
databases/adabase
databases/apq
databases/apq-mysql
databases/apq-odbc
databases/apq-pgsql
devel/ada-util

Remove # $FreeBSD$ from Makefiles.

Bump PORTREVISIONs of all users of math/mpc that we just updated to
version 1.1.0 (via revision 464079).

Return ports maintained by John Marino to the pool, he is no longer interested.

Submitted by:	Mark Millard via private e-mail

Return the ports mistakenly reset to ports@ in r433856 to John Marino.

The mistake was completely on my part, I somehow connected the dots the
wrong way in my head.

The only exceptions (for now) are archivers/zstd and ports-mgmt/synth
which were already picked up by new volunteers in the mean time.

Return ports maintained by John Marino to the pool, see r433827 for details

lang/asis: Upgrade version 2015 => 2016

Bump ports that depend on ASIS as well.

Change Ada Framework foundation from gcc5-aux to gcc6-aux

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).

Remove ${PORTSDIR}/ from dependencies, categories r, s, t, and u.

With hat:	portmgr
Sponsored by:	Absolight

- Switch to options helpers
- While here, add some NO_ARCHes

Approved by:	portmgr blanket

textproc/adabrowse: Remove 1-line pkg-plist

Tie libgnat_util.a to libasis

Rather than specify gnat_util every time ASIS is a dependency, set it
as a library dependency for ASIS.  LIB_DEPENDS doesn't work because it
is a static library, so just manually add libgnat_util.a to BUILD_DEPENDS
and RUN_DEPENDS, then adjust 3 ports accordingly.

textproc/adabrowse: switch build to .gpr to avoid ASIS rebuilds

At least with the upcoming gcc49 and ASIS 2013, I've been seeing gmake
Makefile-based builds trying to rebuild ASIS rather than just use the
provided static library.  I don't know what causes that, but I did notice
that it doesn't happen with GNAT project files.

1) Disregard gmake completely and provide a new build.gpr file
   This will work when gcc-aux is moved to gcc49.
2) Add DOCS option and install the html documentation optionally
3) Relocate LICENSE to make portlint happy
4) Using GPR makes this jobs safe (although the job number might be
   limited to 1 anyway in this case)

textproc/adabrowse: Convert to staging

Also update maintainer email to @FreeBSD.org

Add NO_STAGE all over the place in preparation for the staging support (cat:
textproc)

Add new port: textproc/adabrowse

Adabrowse is an Ada to HTML generator typically used to generate
documentation.  It is a dependency for some Ada ports documentation
options, such as the coming upgrade for security/libsparkcrypto port.

Approved by:	bapt (mentor)