valgrind: needs kernel headers (and doesn't respect CFLAGS)

package/valgrind/valgrind.mk

@@ -25,6 +25,7 @@ $(VALGRIND_DIR)/.configured: $(VALGRIND_DIR)/.patched
 	(cd $(VALGRIND_DIR); rm -rf config.cache; \
 		$(TARGET_CONFIGURE_OPTS) \
 		$(TARGET_CONFIGURE_ARGS) \
+		CC="$(TARGET_CC) $(TARGET_CFLAGS) -I$(LINUX_HEADERS_DIR)/include" \
 		./configure \
 		--target=$(GNU_TARGET_NAME) \
 		--host=$(GNU_TARGET_NAME) \