Fix some of the included assembly files

[Grissess]

There appear to be minor issues with assembly using asl 1.42 Beta (the "current" version as of right now). They're easily enough squelched, though I'm a little concerned that I cannot find a replacement (or even documentation) for the pagefit instruction, which appears to be a pseudoinstruction anyway.

[bill2009]

Hi graham. Thanks. pagefit is a macro that makes sure there are nn bytes left on a page. It's in lcc1802proloCX.inc and later versions. when i put it into IO1802.inc i forgot that file was included into earlier targets. I probably should formally deprecate them or remove them.
I'm fine with removing dubdabx as proposed if it doesn't cause problems with the CX and PX targets.
pagefit: macro bytesneeded
if ($#256)>(255-bytesneeded)
align 256,0xe2
endif
endm

[Grissess]

Hi graham. Thanks. pagefit is a macro that makes sure there are nn bytes left on a page. It's in lcc1802proloCX.inc and later versions. when i put it into IO1802.inc i forgot that file was included into earlier targets.

D'oh, here I was looking through asls sources and not finding anything :)

The implementation seems generic enough; could it be promoted safely to IO1802.inc or any dependency thereof? I'll include that in this PR if desired, it seems simple enough.

I probably should formally deprecate them or remove them.

Most of this is on behalf of a friend of mine using the DH target. I personally know very little about the platform, nor if DH has a usable successor, nor even what DH means, but I'll just report that here for your info.

I'm fine with removing dubdabx as proposed if it doesn't cause problems with the CX and PX targets.

I searched in all files for _dubdabx and found the redundant implementation only in the three changed files. The others didn't seem to have it (by that name) at all. I'm assuming the implementation in nstdlib.inc is still suitable :)