RFE: minimze ebitmap serialization

[cgzones]

Maybe with one of the next kernel policy format changes one could minimize the ebitmap serialization.

Currently each serialized ebitmap contains the mapsize (which could be included once in the policy header) and the hightbit (which can be computed from the highest node plus the mapsize).

For example the current Reference policy compiles to a 1.9M file with 6970 ebitmaps, so 6970 * 2 * 4Byte - 4Byte (~ 2.9%) can be saved.