cooker.py: Allow the -e option to work with virtual classes and -b

Using bitbake -e -b virtual:xxxx:/path/to/the.bb would result in
zero matches since the virtual:xxxx piece wasn't being processed.

This adds in the necessary functionality to handle it correctly.

[YOCTO #1793]

(Bitbake rev: bd5a727c8447bcb747c1d2463b7de2ab6d21a7de)

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

bitbake/lib/bb/cooker.py

@@ -288,7 +288,9 @@ class BBCooker:
             self.status = bb.cache.CacheData(self.caches_array)
             self.handleCollections( bb.data.getVar("BBFILE_COLLECTIONS", self.configuration.data, 1) )
 
-            fn = self.matchFile(buildfile)
+            fn, cls = bb.cache.Cache.virtualfn2realfn(buildfile)
+            fn = self.matchFile(fn)
+            fn = bb.cache.Cache.realfn2virtual(fn, cls)
         elif len(pkgs_to_build) == 1:
             self.updateCache()