manifest: Track our own external/ppp

* Necessary in order to patch CVE-2020-8597

Change-Id: I482a1b12d1e613901b774e786f8aab1858ac7295
diff --git a/default.xml b/default.xml
index eab1d16..d9c9f2b 100644
--- a/default.xml
+++ b/default.xml
@@ -291,7 +291,7 @@
   <project path="external/perfetto" name="platform/external/perfetto" groups="pdk" remote="aosp" />
   <project path="external/piex" name="platform/external/piex" groups="pdk" remote="aosp" />
   <project path="external/ply" name="platform/external/ply" groups="pdk" remote="aosp" />
-  <project path="external/ppp" name="platform/external/ppp" groups="pdk" remote="aosp" />
+  <project path="external/ppp" name="LineageOS/android_external_ppp" groups="pdk" />
   <project path="external/proguard" name="platform/external/proguard" groups="pdk" remote="aosp" />
   <project path="external/protobuf" name="platform/external/protobuf" groups="pdk" remote="aosp" />
   <project path="external/protobuf-javalite" name="platform/external/protobuf-javalite" groups="pdk" remote="aosp" />