Fix a few more targets affected by the change to the TC_CONS_FIX_NEW macro.

	* config/tc-rl78.h (TC_CONS_FIX_NEW): Add RELOC parameter.
	* config/tc-z80.h (TC_CONS_FIX_NEW): Discard RELOC parameter.
	* config/tc-aarch64.h (TC_CONS_FIX_NEW): Discard RELOC parameter.
	* read.c (emit_expr_fix): Mark the r parameter as potentially
	unused.