build-sys: must link with -fstack-protector

It is needed to give that flag to the linker as well, but latest
libtool 2.4.2 still swallows that argument, so let's pass it with
libtool -Wc argument.

qemu-1.4.0/stubs/arch-query-cpu-def.c:6: undefined reference to `__stack_chk_guard'

Signed-off-by: Marc-André Lureau <mlureau@redhat.com>
Reviewed-by: Alon Levy <alevy@redhat.com>
diff --git a/rules.mak b/rules.mak
index edc2552..36aba2d 100644
--- a/rules.mak
+++ b/rules.mak
@@ -36,6 +36,7 @@
        $(if $(filter %.lo %.la,$^),$(LIBTOOL) --mode=link --tag=CC \
        )$(CC) $(QEMU_CFLAGS) $(CFLAGS) $(LDFLAGS) -o $@ \
        $(sort $(filter %.o, $1)) $(filter-out %.o, $1) $(version-obj-y) \
+       $(if $(filter %.lo %.la,$^),$(LIBTOOLFLAGS)) \
        $(LIBS),$(if $(filter %.lo %.la,$^),"lt LINK ", "  LINK  ")"$(TARGET_DIR)$@")
 endif