shells/44bsd-csh: Chase b0d746a, remove USES=sbrk

USES=sbrk documents the ports that still need sbrk remediation. It
also flags riscv and aarch64 as BROKEN.

Noted by:	brooks

shells/44bsd-csh/Makefile

@@ -9,7 +9,7 @@ COMMENT=	The traditional 4.4BSD /bin/csh C-shell
 
 EXTRACT_DEPENDS=	rcs:devel/rcs57
 
-USES=		sbrk tar:bzip2
+USES=		tar:bzip2
 LDFLAGS=	-Wl,--allow-multiple-definition
 NO_WRKSUBDIR=	yes
 PORTDOCS=	paper.ascii.gz