[oe] DISTRO_PR, ipkg dependencies, and meta toolchains...

[Mike (mwester)]

Consider the control data for openssl-dev (exerpts):

Package: openssl-dev
Version: 0.9.7g-r7.1
...
Depends: openssl (= 0.9.7g-r7), libcrypto0.9.7, libssl0.9.7
Recommends: libc6-dev, libgcc-dev, libcrypto-dev...

Note in particular the openssl-dev version number, which has the
DISTRO_PR appended to make it "-r7.1" instead of just "-r7".

But in the dependencies, it lists the specific version of the
corresponding runtime -- without the DISTRO_PR.  And of course, that
specific version doesn't exist (or rather, if it exists in someone's
environment, it would be a left-over ipkg from before the DISTRO_PR was
added).

One place this bites us is in the SDK assembling (bitbake
meta-toolchain-<whatever>):

| Collected errors:
|  * ERROR: Cannot satisfy the following dependencies for
task-fso-toolchain-target:
|        *  openssl (= 0.9.7g-r7) *

Poking about I can find a place in the appropriate bbclass files to hack
things up so that my specific problem will be resolved -- but I'd prefer
that someone who understands just how much of the rdepends/rrecommends
needs this treatment offer some advice first.  (And of course, I should
warn anyone who cares that I know Perl far better than Python, a fact
that would almost certainly end up reflected in the patch I would write!)

Mike (mwester)