package/mpfr: fix make source-check/external-deps issue

package/mpfr/mpfr.mk

@@ -22,8 +22,10 @@ MPFR_PATCH_SOURCE:=$(DL_DIR)/$(MPFR_PATCH_FILE)
 
 $(MPFR_PATCH_SOURCE):
 	$(call DOWNLOAD,$(MPFR_SITE),$(MPFR_PATCH))
+ifeq ($(SPIDER),) # this breaks source-check/external-deps
 	mv $(DL_DIR)/$(MPFR_PATCH) $@
 endif
+endif
 
 $(DL_DIR)/$(MPFR_SOURCE):
 	 $(call DOWNLOAD,$(MPFR_SITE),$(MPFR_SOURCE))