Big autotool update:

Big autotool update:

* Upgraded to the latest version of autoconf, automake and libtool

* replaced pthread detection code in configure with a more effective one

* added a test to see if special solaris defines
  are required for ctime_r to behave posixly correct.

* Fixed lots of warnings from autotools

* started adding support for pkg-config ... this will eventually
  make the whole library finding much simpler

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@305 a5681a0c-68f1-0310-ab6d-d61299d08faa