Option to build Master without --enable-maintainer-mode

[Jeffrey Walton]

I am trying to build GnuPG and its components from Git Master.
According to README.git [1], one must configure master using
--enable-maintainer-mode.

Maintainer mode causes a lot of problems in practice. I'm not a
maintainer and I am not interested in building release tarballs or
documentation. However, maintainer mode requires that I have a well
configured machine to do so. Some machines I test on do not have the
tools available. Other machines I have are resource constrained and I
don't want to waste the cpu cycles to build the docs. Other machines I
have lack the storage and quickly run out of disk space due to
unneeded documentation. Finally, due to bugs with GhostScript and
Convert, the docs don't even build on some platforms due to some
policy decision.

The README.git also say we must './configure --enable-maintainer-mode'
to install missing files. This is not true:

    # Satisfy requirements, install missing files
    ./configure --enable-maintainer-mode
    # Now build for real
    ./configure && make -j 8

The files are still missing after './configure
--enable-maintainer-mode'. The regular 'configure && make' will still
fail due to missing files.

I think the project needs to supply a --enable-qa-mode so folks like
me can test the sources without futzing around with release tarballs
or documentation.

If interested, here is the carnage --enable-maintainer-mode causes:
https://travis-ci.org/github/noloader/gnupg/builds/670053355 . The
GitHub fork repeatedly builds the entire GnuPG suite using Travis jobs
in different configurations. The red X's indicate failed builds. Most
of the failures are due to problems in building the docs.

[1] https://git.gnupg.org/cgi-bin/gitweb.cgi?p=gnupg.git;a=blob;f=README.GIT;h=57dab7a213c48884dec8b73ea17ca563c3d77908;hb=HEAD