Reduce libkafel.so size

Currently `libkafel.so` takes 440KiB (`x86_64`, release, stripped) which seems superfluous.

On top of that, it has 7122 relocations and relocation definitions themselves take 167KiB. This has runtime cost as well.

Proposal:

* exploit redundancy in the data set to reduce the footprint;

* get rid of relocations — instead of storing string pointers in tables use integral offsets in a string pool. The later is cumbersome to do manually, use code generation.