smallc: remove literal buffer

smallc: remove literal buffer

Restructure the code so that literal data is generated inline relying upon the
assembler segment functionality to sort out the interleaving. A platform whose
assembler isn't good enough can always switch between two files...

This saves us about 3K and means that the literal space is no longer limited
to 2.5K per compiled file.

You stil can't initialize pointers but the framework is now there to do this.