manifest: track our own system/core

Change-Id: Ia2cbc7618b1429fd23d926853442f18cbaad4a4b
Signed-off-by: Alexander Martinz <amartinz@shiftphones.com>
diff --git a/snippets/shift.xml b/snippets/shift.xml
index 415fcef..0ff4cc2 100644
--- a/snippets/shift.xml
+++ b/snippets/shift.xml
@@ -59,6 +59,7 @@
   <project path="packages/overlays/SHIFT" name="SHIFTPHONES/android_packages_overlays_SHIFT" remote="shift" />
 
   <!-- System -->
+  <project path="system/core"          name="SHIFTPHONES/android_system_core"          remote="shift" />
   <project path="system/libhidl"       name="SHIFTPHONES/android_system_libhidl"       remote="shift" />
   <project path="system/sepolicy"      name="SHIFTPHONES/android_system_sepolicy"      remote="shift" />
   <project path="system/update_engine" name="SHIFTPHONES/android_system_update_engine" remote="shift" />