MFC 278582:

MFi386:
When building some of the boot loaders with clang, and DEBUG_FLAGS or
CFLAGS having '-g' in it, clang outputs several assembly directives that
are too new for our version of binutils.

Therefore, assemble the resulting .s files with clang instead.  A more
general solution can be implemented when a GNU as-compatible driver for
clang's integrated assembler appears.

sys/boot/pc98/boot2/Makefile

@@ -93,6 +93,7 @@ boot2.out: ${BTXCRT} boot2.o sio.o
 	${LD} ${LD_FLAGS} -Ttext ${ORG2} -o ${.TARGET} ${.ALLSRC}
 
 boot2.o: boot2.s
+	${CC} ${ACFLAGS} -c boot2.s
 
 SRCS=	boot2.c boot2.h