Add libvintf groups="pdk".

Bug: 34718809

default.xml

@@ -536,7 +536,7 @@
   <project path="system/libhidl" name="platform/system/libhidl" />
   <project path="system/libhwbinder" name="platform/system/libhwbinder" groups="pdk" />
   <project path="system/libufdt" name="platform/system/libufdt" groups="pdk" />
-  <project path="system/libvintf" name="platform/system/libvintf" />
+  <project path="system/libvintf" name="platform/system/libvintf" groups="pdk" />
   <project path="system/media" name="platform/system/media" groups="pdk" />
   <project path="system/nativepower" name="platform/system/nativepower" />
   <project path="system/netd" name="platform/system/netd" groups="pdk" />