rewrite lsrc in C for pure, raw speed

For now the C version of lsrc is a straight port of the shell version

The C version is significantly faster:

C
  lsrc -F  0.02s user 0.02s system 69% cpu 0.046 total

sh
  lsrc -F  16.01s user 7.15s system 114% cpu 20.235 total