Add dexdiag tool to images

Allow on-device analysis of dex memory usage by adding dexdiag to the
image.

Bug: 38181622
Test: adb shell "dexdiag"
Change-Id: I2142b5e42eae8cc01755d0e86c179c2fa86be00c
diff --git a/target/product/runtime_libart.mk b/target/product/runtime_libart.mk
index f8f8bda..0755bf3 100644
--- a/target/product/runtime_libart.mk
+++ b/target/product/runtime_libart.mk
@@ -63,6 +63,7 @@
 # ART/dex helpers.
 PRODUCT_PACKAGES += \
     ahat \
+    dexdiag \
     dexdump \
     dexlist \
     hprof-conv \