Allow "make check" to work with XL
Allow "make check" to work with XL

This patch corrects a few things so that a temporary installation of XL is
created and configured properly for "make check" to run fine.

Patch from Jov.

postmind-net/postgres-xl,kmjungersen/PostgresXL,postmind-net/postgres-xl,arcivanov/postgres-xl,kmjungersen/PostgresXL,kmjungersen/PostgresXL,snaga/postgres-xl,arcivanov/postgres-xl,kmjungersen/PostgresXL,snaga/postgres-xl,arcivanov/postgres-xl,kmjungersen/PostgresXL,snaga/postgres-xl,arcivanov/postgres-xl,postmind-net/postgres-xl,postmind-net/postgres-xl,arcivanov/postgres-xl,postmind-net/postgres-xl,snaga/postgres-xl,snaga/postgres-xl,arcivanov/postgres-xl