[development] hook_install: pgsql: check version number

[Keve]

Hi,

I am not very familiar with Postgresql.
I wrote taxonomy_access.install file, but for POSTGRESQL priot to 8.0, I 
need to make a BIT_OR aggregate function.
Do you think this will work OK for pg?

      if (version_compare(pg_version(), '8.0', '<')) {
           // PRIOR TO POSTGRESQL 8.0: making a BIT_OR aggregate function
      }

Many thanks,
Keve.