Throw out IF DOS5 statements?

[boeckmann]

My impression is that the kernel does not work anyway when compiling without the DOS5 definition. Something like the following looks wrong when compiling without DOS5 definition. At least it is not obvious to me that the high byte of DDSC_NFATRECS contains zero if the low byte gets assigned only AL.

edrdos/drdos/funcs.fdo

Lines 2047 to 2055 in e85d927

	if DOS5
	mov es:DDSC_NFATRECS[di],ax ; set FAT size
	else
	mov es:DDSC_NFATRECS[di],al ; set FAT size
	endif
	; mov es:word ptr DDSC_BFATRECS[di],ax ; FAT size (32-bit)
	; mov es:word ptr DDSC_BFATRECS+2[di],0
	mov ax,es:word ptr DDSC_NFATRECS[di]

[boeckmann]

DOS5 definition is removed from the current DRBIO source. I will also remove it from DRDOS when porting it to JWasm.

[boeckmann]

All DOS5 ifdefs are gone.