[ This description should have been on the earlier fork/exec

[ This description should have been on the earlier fork/exec
  commit, but I am adding it now so it is in CVS.]

The patch basically is a slight rearrangement of the code to allow
fork/exec on Unix, with the ultimate goal of doing CreateProcess on
Win32.  The changes are:

        o  Write out postmaster global variables and per-backend
variables to be read by the exec'ed backend

        o  Mark some static variables as global when exec is used so
then can be dumped from postmaster.c, marked NON_EXEC_STATIC

        o  Remove value passing with -p now that we have per-backend
file

        o  Move some pointer storage out of shared memory for easier
dumping.

        o  Modified pgsql_temp directory cleanup to handle per-database
directories and the backend exec directory under datadir.

Claudio Natoli