package_ipk/deb: Fix specific version handling

package_ipk/deb: Fix specific version handling

We recently added a "xxx (= 1.2.3)" style dependency to a recipe and have
been having trouble with the opkg and debian backends with it.

The issues is that for debian, "=" really does mean equals and includes the
PR field. One bitbake recipe does not know the PR of another, nor shoud it.
In other words 1.2.3 != 1.2.3-r0. Debian defaults to a PR of "0", not our
"r0".

The only way I can think of to make this work is to change "=" dependencies
without revision information (no "-r" in the version) into things like:
"xxx (>= 1.2.3), xxx (<< 1.2.3.0)". This appears to work even if it is a
pretty horrible workaround.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>