Add clone-depth to platform/prebuilts/android-emulator

Change-Id: I3666d8a70dbeee029002bf1e764aa2616b16f45d
diff --git a/default.xml b/default.xml
index 4e3aab4..a37ef1e 100644
--- a/default.xml
+++ b/default.xml
@@ -375,7 +375,7 @@
   <project path="packages/wallpapers/NoiseField" name="platform/packages/wallpapers/NoiseField" />
   <project path="packages/wallpapers/PhaseBeam" name="platform/packages/wallpapers/PhaseBeam" />
   <project path="pdk" name="platform/pdk" groups="pdk" />
-  <project path="prebuilts/android-emulator" name="platform/prebuilts/android-emulator" />
+  <project path="prebuilts/android-emulator" name="platform/prebuilts/android-emulator" clone-depth="1" />
   <project path="prebuilts/clang/darwin-x86/3.1" name="platform/prebuilts/clang/darwin-x86/3.1" groups="pdk,darwin" />
   <project path="prebuilts/clang/darwin-x86/3.2" name="platform/prebuilts/clang/darwin-x86/3.2" groups="pdk,darwin" />
   <project path="prebuilts/clang/darwin-x86/arm/3.3" name="platform/prebuilts/clang/darwin-x86/arm/3.3" groups="darwin,arm" />