automake: update dist checks for recent changes

Various files have been added and removed causing the dist and distcheck
Make targets to fail.  This commit fixes dist; distcheck is improved but
is not complete because the bindings Makefile.am assumes the build is
performed in the source tree.  (Standard autotool practice now is to
require support for separated builds.)

Signed-off-by: Peter A. Bigot <pab@pabigot.com>
autoconf: rework config file locations

If we assume somebody puts the src directory in the include file path to
CC, we don't need relative symlinks to rrd_config.h which will make
separated builds much easier to support.  Then we don't need to have the
config files in the root directory and symlinks back and forth between
there and src.

Signed-off-by: Peter A. Bigot <pab@pabigot.com>
gitignore: add for lua and ruby bindings
automake: rework for separated builds

Standard practice (including the assumptions of make distcheck) is that
the system can be built in an out-of-tree directory referencing sources
in a read-only filesystem.  The language-specific bindings build
infrastructure, particularly for perl, makes that difficult but
achievable.

Signed-off-by: Peter A. Bigot <pab@pabigot.com>
automake: full support for make check

Presence of the TESTS variable adds check as a target, but for this to
work completely all the test infrastructure needs to be part of the
distribution package, which is easiest if there's a Makefile.am in that
directory.

Signed-off-by: Peter A. Bigot <pab@pabigot.com>
gitigore: add doc files created only by make dist
make distcheck: complete updates required for support

Rework the tests so they can run in a situation where the source tests
directory is read-only.  Also fix a couple minor issues with make
distclean and make distuninstallcheck.

Signed-off-by: Peter A. Bigot <pab@pabigot.com>
Merge pull request #475 from pabigot/fix-dist

Fix autotools dist support