Suppress the warning when copying init.recovery.*.rc.

The file is optional, and we already ignore the cp result.

cp: cannot stat 'out/target/product/taimen/root/init.recovery.*.rc': No such file or directory

Test: `m -j bootimage` with aosp_taimen-userdebug. No more warning.
Change-Id: I815c6e0ff8d432123066cf4a44a8638dc94c96d5
diff --git a/core/Makefile b/core/Makefile
index 40f252f..309804c 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1544,7 +1544,7 @@
   # Removes $(TARGET_RECOVERY_ROOT_OUT)/init*.rc EXCEPT init.recovery*.rc.
   $(hide) find $(TARGET_RECOVERY_ROOT_OUT) -maxdepth 1 -name 'init*.rc' -type f -not -name "init.recovery.*.rc" | xargs rm -f
   $(hide) cp -f $(recovery_initrc) $(TARGET_RECOVERY_ROOT_OUT)/
-  $(hide) cp $(TARGET_ROOT_OUT)/init.recovery.*.rc $(TARGET_RECOVERY_ROOT_OUT)/ || true # Ignore error when the src file doesn't exist.
+  $(hide) cp $(TARGET_ROOT_OUT)/init.recovery.*.rc $(TARGET_RECOVERY_ROOT_OUT)/ 2> /dev/null || true # Ignore error when the src file doesn't exist.
   $(hide) mkdir -p $(TARGET_RECOVERY_ROOT_OUT)/res
   $(hide) rm -rf $(TARGET_RECOVERY_ROOT_OUT)/res/*
   $(hide) cp -rf $(recovery_resources_common)/* $(TARGET_RECOVERY_ROOT_OUT)/res