build: make the touch .autoremove call non-fatal

Fixes build issues when there is nothing to do on the compile step (e.g.
with unselected packages).

Signed-off-by: Felix Fietkau <nbd@nbd.name>

include/package.mk

@@ -216,7 +216,7 @@ define Build/CoreTargets
 
   ifneq ($(CONFIG_AUTOREMOVE),)
     compile:
-		touch $(PKG_BUILD_DIR)/.autoremove
+		-touch $(PKG_BUILD_DIR)/.autoremove 2>/dev/null >/dev/null
 		$(FIND) $(PKG_BUILD_DIR) -mindepth 1 -maxdepth 1 -not '(' -type f -and -name '.*' -and -size 0 ')' -and -not -name '.pkgdir' | \
 			$(XARGS) rm -rf
   endif