Add art-tools to host build outputs

Building of host tools stopped when moving to APEX. This change
re-enables building of host tools.

Bug: 128990084
Test: m -j72 && find out -name 'oatdump'
Change-Id: Iad42b4e36561001709634174014192e56a64aafd
diff --git a/target/product/base_system.mk b/target/product/base_system.mk
index 83a84f7..897f8ec 100644
--- a/target/product/base_system.mk
+++ b/target/product/base_system.mk
@@ -282,6 +282,7 @@
     BugReport \
     adb \
     adbd \
+    art-tools \
     atest \
     bcc \
     bit \