Update d/b/test-patches to work with current package
d/b/test-patches stopped working properly:
- It fails to detect the running kernel's flavour if its release string doesn't have an ABI number
- It writes old-style
defines
files to restrict the featuresets and flavours built, but these no longer have any effect
Fix both of these problems. For consistency with the added code, also remove obsolete featureset names from the featureset detection.