contrib/contrib-global.mk library and _generally_ behave like
   Makefiles for other contrib modules.
   Besides it fixes Perl's interpolation of $libdir variable, which
   should be passed to backend instead. This patch is done against
   PostgreSQL 7.3b2

   Besides, I want to thank Peter Eisentraut for his very friendly and
   helpful attitude and politely ask him to check whether contrib
   modules actually continue to work after he implements another
   major change to their build process.

Alexey Borzov