Remove dependency on libreadline5-dev from Debian and Ubuntu.

libreadline5-dev is old and superseded by libreadline-dev.

Also OpenSRF installs libreadline-dev, so we should not have to
install it from Evergreen's Makefile.install.

Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>
Signed-off-by: Ben Shum <bshum@biblio.org>