This implements a feature similar to BBCLASSEXTEND, but for generating
multiple versions of a given recipe.  For example: BBVERSIONS = "1.0 2.0 git".

In addition to the above, one can utilize [a-b] style patterns, and can have a
:<basever> postfix, which allows you to essentially name the range of
versions.  Both the current version and the basever end up in OVERRIDES, and
the basever gets placed into the BPV variable.  The default BPV, if none is
specified, is the original PV of the recipe, before bbversions processing.

In this way, you can do things like:
BBVERSIONS = "1.0.[0-6]:1.0.0+
              1.0.[7-9]:1.0.7+"

SRC_URI_append_1.0.7+ = "file://some_extra_patch.patch;patch=1"

Or you can create a recipe per range, and name the recipe file as such: nano_1.0.7+.bb.

(Bitbake rev: 4ee9a56e16f1eb3c1649eaa3127b09ab0e93d1ec)

Signed-off-by: Chris Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>