manifest: Switch to our fork of art

* Required for adding support for sdm845 platform
   (see Change-Id: Iad0dc93b4e99fe17af16cda5316b06ae4f17aa2c)

Change-Id: Ic9fc7218d74d6d61092ee377525f4af8928c9f1c

default.xml

@@ -35,7 +35,7 @@
     <linkfile src="root.bp" dest="Android.bp" />
     <linkfile src="bootstrap.bash" dest="bootstrap.bash" />
   </project>
-  <project path="art" name="platform/art" groups="pdk" remote="aosp" />
+  <project path="art" name="LineageOS/android_art" groups="pdk" />
   <project path="bionic" name="LineageOS/android_bionic" groups="pdk" />
   <project path="bootable/recovery" name="LineageOS/android_bootable_recovery" groups="pdk" />
   <project path="compatibility/cdd" name="platform/compatibility/cdd" groups="pdk" remote="aosp" />