* configure.in: $srcdir != $builddir fix for GIMP_CONTRIBUTORS

* plug-ins/common/plugin-defs.pl: More tidying up after Daniel Egger

* tools/pdbgen/Makefile.am: parse pdb defs only once for app and lib

* tools/pdbgen/lib.pl
* tools/pdbgen/pdb/procedural_db.pdb: all void rets now return a
boolean for success/failure

-Yosh