Mark more targets as PHONY

So that we can start restricting non-phony targets to $OUT_DIR and
$DIST_DIR.

Test: add --writable=out/, see fewer warnings
Change-Id: I411fe4af732b1bce35d4a4c1e2a47b5f8a15e6b8
diff --git a/core/main.mk b/core/main.mk
index fb845df..160737a 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -1352,7 +1352,8 @@
 # umbrella targets to assit engineers in verifying builds
 .PHONY: java native target host java-host java-target native-host native-target \
         java-host-tests java-target-tests native-host-tests native-target-tests \
-        java-tests native-tests host-tests target-tests tests java-dex
+        java-tests native-tests host-tests target-tests tests java-dex \
+        native-host-cross
 # some synonyms
 .PHONY: host-java target-java host-native target-native \
         target-java-tests target-native-tests