Consider generating lib/data.c and lib/tr46map_data.c in some interpreted language for cross-builds

Generating these files currently require a pass with the host compiler. If these files could be generated from a simple shell script (or more likely a perl or python script) that would simplify cross-builds. Right now cross-builds require a two-step phase, which should work fine but is inefficient.

Background: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1100478