libffi: fix staging headers cleanup

The LIBFFI_MOVE_STAGING_HEADERS function is responsible for moving
around libffi headers to a standard location. Once this is done, it
removes the no longer used directory, but does so in $(TARGET_DIR) and
not $(STAGING_DIR). This directory is already cleaned up in
$(TARGET_DIR) in the LIBFFI_REMOVE_TARGET_HEADERS post-install target
hook.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libffi/libffi.mk

@@ -17,7 +17,7 @@ define LIBFFI_MOVE_STAGING_HEADERS
 	mv $(STAGING_DIR)/usr/lib/libffi-$(LIBFFI_VERSION)/include/*.h $(STAGING_DIR)/usr/include/
 	$(SED) '/^includedir.*/d' -e '/^Cflags:.*/d' \
 		$(STAGING_DIR)/usr/lib/pkgconfig/libffi.pc
-	rm -rf $(TARGET_DIR)/usr/lib/libffi-*
+	rm -rf $(STAGING_DIR)/usr/lib/libffi-*
 endef
 
 LIBFFI_POST_INSTALL_STAGING_HOOKS += LIBFFI_MOVE_STAGING_HEADERS