Add external/adt-infra to manifest

Bug: 24718114

default.xml

@@ -59,6 +59,7 @@
   <project path="device/sample" name="device/sample" groups="pdk" />
   <project path="docs/source.android.com" name="platform/docs/source.android.com" groups="pdk-cw-fs,pdk-fs" />
   <project path="external/aac" name="platform/external/aac" groups="pdk" />
+  <project path="external/adt-infra" name="platform/external/adt-infra" groups="adt-infra,notdefault" />
   <project path="external/android-clat" name="platform/external/android-clat" groups="pdk-cw-fs,pdk-fs" />
   <project path="external/android-mock" name="platform/external/android-mock" groups="pdk-cw-fs,pdk-fs" />
   <project path="external/androidplot" name="platform/external/androidplot" groups="pdk-cw-fs,pdk-fs" />