Add clone-depth="1" to prebuilts/qemu-kernel

Change-Id: I212284ee87d823f9dda0c94114715d084eb3fd25

default.xml

@@ -447,7 +447,7 @@
   <project path="prebuilts/ndk" name="platform/prebuilts/ndk" groups="pdk" />
   <project path="prebuilts/python/darwin-x86/2.7.5" name="platform/prebuilts/python/darwin-x86/2.7.5" groups="darwin" />
   <project path="prebuilts/python/linux-x86/2.7.5" name="platform/prebuilts/python/linux-x86/2.7.5" groups="linux" />
-  <project path="prebuilts/qemu-kernel" name="platform/prebuilts/qemu-kernel" groups="pdk" />
+  <project path="prebuilts/qemu-kernel" name="platform/prebuilts/qemu-kernel" groups="pdk" clone-depth="1" />
   <project path="prebuilts/runtime" name="platform/prebuilts/runtime" />
   <project path="prebuilts/sdk" name="platform/prebuilts/sdk" groups="pdk" />
   <project path="prebuilts/tools" name="platform/prebuilts/tools" groups="pdk,tools" />