Optimize Linker by Resolving Some Patches at Assembly Time

[Hawkbat]

Some patches don't need to be deferred to the linker because they aren't actually dependent on imported symbols, but just use symbols that aren't defined until later in the file. For example, this is currently resolved at assembly time:

Start:
    ds 10
End:
ld c, End - Start

But this is resolved at linker time unnecessarily:

ld c, End - Start
Start:
    ds 10
End:

The assembler could instead do a post-processing pass to resolve and remove any patches which don't involve imported symbols.