[IA64] don't assume that unwcheck.py is executable

Don't assume that this file has execute permissions.  For example, patch(1)
loses that information.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/Makefile

@@ -77,7 +77,7 @@ vmlinux.gz: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $@
 
 unwcheck: vmlinux
-	-$(Q)READELF=$(READELF) $(srctree)/arch/ia64/scripts/unwcheck.py $<
+	-$(Q)READELF=$(READELF) python $(srctree)/arch/ia64/scripts/unwcheck.py $<
 
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)