Log Message:
Update to 0.9.3. Changes:
 * Portability fixes.
 * Pth is not anymore linked by means of weak symbol tricks.  It is
   now required to link to the pth version of libassuan.  New aufoconf
   macros are provided to to check for this.  The pth version is only
   build if Pth is available.
 * configure does now check that descriptor passing is available.  A
   way to check at runtime for this is also provided