These targets don't work with eng checkbuilds, so disable them.

This unbreaks eng checkbuilds after https://r.android.com/2822402

Test: lunch aosp_panther-trunk_staging-eng ; m checkbuild
Change-Id: I3b835e5a8468153ac459e6b03624ae4e582cada1
diff --git a/Android.mk b/Android.mk
index e47c9ce..7e5903a 100644
--- a/Android.mk
+++ b/Android.mk
@@ -752,6 +752,10 @@
 # Clear locally used variables.
 TEST_ART_TARGET_SYNC_DEPS :=
 
+# These files only exist if this flag is off. WITH_DEXPREOPT_ART_BOOT_IMG_ONLY is the
+# minimal dexpreopt mode we use on eng builds for build speed.
+ifneq ($(WITH_DEXPREOPT_ART_BOOT_IMG_ONLY),true)
+
 # Helper target that depends on boot image creation.
 #
 # Can be used, for example, to dump initialization failures:
@@ -767,6 +771,8 @@
   $(HOST_OUT_EXECUTABLES)/dex2oatds \
   $(HOST_OUT_EXECUTABLES)/profman
 
+endif # TARGET_BUILD_VARIANT == eng
+
 ########################################################################
 
 # Build a target that contains dex public SDK stubs for SDK version in the list.