[cc2] Do not use size2asm in default initializer
[cc2] Do not use size2asm in default initializer

QBE IR lacks fill with value command, so the previous
implementation was wrong. This implementation takes
the approach of using always a fill command with any
non initialized data. It is simpler for us, and it
is simpler for QBE.

k0gaMSX/scc,k0gaMSX/scc,k0gaMSX/scc