BUG #7822: PGDG packaged postgresql92 binaries do not find their libraries

The following bug has been logged on the website:

Bug reference: 7822
Logged by: Georgi Georgiev
Email address: georgi-georgiev-pgsql(at)japannext(dot)co(dot)jp
PostgreSQL version: 9.2.2
Operating system: CentOS 6.3
Description:

The postgresql92 package would configure the postgresql92-libs libraries for
system-wide use (using update-alternatives in the post-install scriptlet),
but it does not run ldconfig, so the binaries cannot find their libraries.
In short, "psql" is unusable.

Steps to reproduce:

Remove all postgresql libraries:
$ sudo yum remove -y postgresql\*

Install the PGDG 9.2 binaries
$ sudo yum install -y postgresql92

Verify that the psql binary is not properly linked:
$ ldd /usr/bin/psql | head -n2
linux-vdso.so.1 => (0x00007fffb27ff000)
libpq.so.5 => not found

The ld.so.conf.d update should probably be moved to the postgresql92-libs
packages, as this would allow other packages that require libpq.so.5 to keep
working (like php-pgsql and perl-DBD-Pg).