Fix cross link using host-cross ar

If building on 32bit host and creating 64bit libraries, the target
package builds should not invoke the 32bit hosts's ar.  Specifically
you will get an error message like:

x86_64-linux-gcc  -m64 --sysroot=/opt/qemux86-64/tmp/sysroots/qemux86-64 -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed -Llibs/x86emu v86_x86emu.o v86_mem.o v86_common.o  v86.o -lx86emu -o v86d
libs/x86emu/libx86emu.a: could not read symbols: Archive has no index; run ranlib to add one
collect2: error: ld returned 1 exit status

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

Upstream-Status: Pending

---
 libs/x86emu/Makefile |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/libs/x86emu/Makefile
+++ b/libs/x86emu/Makefile
@@ -1,7 +1,11 @@
 OBJS = decode.o fpu.o ops.o ops2.o prim_ops.o sys.o
 
+ifeq ($(AR),)
+	AR = ar
+endif
+
 libx86emu.a: $(OBJS)
-	ar rv $@ $+
+	$(AR) rv $@ $+
 
 %.o: %.c
 	$(CC) -c $(CFLAGS) -o $@ $<