build: fix build on rhel5 and older distros

rpmbuild/rpm are not as kind as on newer distros.

Move BuildR* on top otherwise they are not seen by rpm*.

Add a check to error out if we cannot detect basic distro information.
On rhel5/centos5 information such as dist/rhel/centos_version are not
defined by default.

Fix conf_opt_rsctmpdir check and definition.

Fix JFLAGS check and definition.

Fix BuildRequires on help2man (not available in rhel5) and drop ocf-tester man
page from rhel5 (cannot be built without EPEL).

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>