.SYM file no crop 32 bits data for negative values

This code works and no warning has generated
```
	PAGE	0
	db 0
	ORG	38h
	db	0C3h
	dw	0FD9Ah
;------------------------------------
; DATA
;------------------------------------
LABEL:
	INCBIN "DATA/file" SKIP 100 ; Total file size 4010 bytes - 100 = 3910 bytes
LABEL1 	equ LABEL - 100
```
LABEL 1 works in other part if the code.
But in .SYM file you find a 32 bits data
`FFFFFFD7h LABEL1`
