Update autoconf macros from upstream.
Display dj-setup-database usage on every error.
Executables now have a type.

The type is one of compare, compile and run. One can view and edit the
type in the web interface but it is not used somewhere (e.g to filter).
Filter executables by type for selects.
Fix list of problems/languages where one executable is used.
Add config checks for executables.
Check on post_max_size in REST API.

The comparison of post_max_size and $_SERVER['CONTENT_LENGTH'] allows
us to give a better error message when a judgedaemon posts too much
data in a single request.
Fix copy/paste bug in dj-setup-database.
Fix m4 macro dependencies after upgrade from upstream in 937d6d315.

Include config.{guess,sub} scripts from automake, required by
the AC_CANONICAL_HOST macro now used in m4/ax_boost_base.m4.

Add AX_REQUIRE_DEFINED m4 macro required by AX_APPEND_*_FLAGS.
Check for flexc++ and bisonc++ and save versions in config.h.
Fix compile error in checktestdata.

Bisonc++ >= 4.02.00 doesn't work with old generated headers
since exceptionHandler is missing.

Flexc++ >= 2.00.00 doesn't work with old generated headers
since postCode is missing.
Include default compare script into database.
Include default float compare script into database.
Directly call command line scripts.

This fixes a potential race condition when running multiple
judgedaemons, where one judgedaemon overwrites the symlink by another
judgedaemon. Also scripts now know can determine their own path.
Directly call compare scripts.
Directly call run scripts.

Also include default run script in database. If existent, the runjury
executable is copied next to the run executable (including the
additional support program runpipe).
Default run/compare script is now configurable.
fetch_executable always returns execrunpath.

It's not longer necessary that calling functions need to know if the
executable is new or not. This cleans up the code a bit.
No script is considered as 'special' for the judgedaemon.

The judgedaemon can handle the compare/run scripts without knowledge
about its type (default or special).