proposal: separate databases for contrib module testing

I'd like to change the way we set the CONTRIB_TESTDB name for contrib 
modules. so that each module doesn't wipe out the previous module's test 
db. The reason is that this will let us test upgrading them using 
pg_upgrade much more easily. Not testing this is a significant hole in 
the pg_upgrade testing regime.

This can be achieved by a fairly simple change in Makefile.global.in 
along these lines:
   ifneq ($(MODULE_big),)      CONTRIB_TESTDB = contrib_regression_$(MODULE_big)   else      ifneq ($(MODULES),)
CONTRIB_TESTDB= contrib_regression_$(MODULES)      else        CONTRIB_TESTDB = contrib_regression      endif   endif
 


plus some changes in the dblink tests / results that rely on the 
database name.

The downside is that this involves in increase in space of 6.5Mb to 
7.5Mb per module. That doesn't seem huge in these days when a standard 
commodity hard drive is 500Gb and up.

Thoughts?

cheers

andrew