Updating rulecompiler makefile:
  o To be configurable for c-compiler and c++-compiler
  o To be configurable for ICU installation
  o Added clean so we can 'make clean' in the rulecompiler
  
Any use after this point is required to also define:
  o MAKEFILE_CC
  
Here's the explanation of what to do for it which is a comment in the
Makefile: