Revert "Add external/xdelta3 and external/syspatch"

This reverts commit d7e5ea0d0c55630df4f0db4010b63b0e44c70486.

Change-Id: I89f89c63cb5473f75ac738d0db1cfde8d7e7cd13
Merge branch 'master' of https://android.googlesource.com/platform/manifest into default