cc2520: fix formating of DriverLayerC.nc
shimmer2: add -I to shimmer2.platform

original conversion to v3 build system missed the -I.
platforms: shimmer2r/span, fix some comments
make: add symbol table and interspersed listing generation

- generate main.sym (symbol tables) and main.lst (interspersed,
  c and assembly) listing.

- update size computation so it outputs both the perl output as
  well as what the toolchain size thinks.