[minicoredumper] Fix some autotools related issues and add coredump rotation

[Juergen Borleis]

Hi,

this set does some changes at the buildsystem level to have it up-to-date.

The last change adds a "rotation" feature to the 'minicoredumper' in order to
support long running systems where sometimes an application crashes, but
noone is looking after it immediately. In this case its possible to limit the
used filesystem space and 'minicrodumper' removes older coredumps in favor of
the new one if the defined filesystem space limit is reached.

This rotation feature is disabled by default to not change the behaviour of
'minicoredumper' by accident. If one wants to make use of it, it must be
enabled at configuration time via the '--enable-rotation' parameter.

In order to handle something like rotation of stored coredumps,
the calculation when to rotate must be atomic from the 'minicoredumper'
point of view. So this change adds an advisory lock, to let only one
instance run at a time. The lock defaults to the '/var/run/lock/' and the
path is required to exist at run-time.

Comments are welcome.

Juergen