Add platform/tools/external_updater to manifest

Change-Id: Ie5706e2b2a48c2aff05290b10a2d5cc8d124373b

default.xml

@@ -652,6 +652,7 @@
   <project path="tools/base" name="platform/tools/base" groups="notdefault,tools" />
   <project path="tools/build" name="platform/tools/build" groups="notdefault,tools" />
   <project path="tools/dexter" name="platform/tools/dexter" groups="tools,pdk-fs" />
+  <project path="tools/external_updater" name="platform/tools/external_updater" groups="tools" />
   <project path="tools/external/fat32lib" name="platform/tools/external/fat32lib" groups="tools" />
   <project path="tools/external/gradle" name="platform/tools/external/gradle" groups="tools" clone-depth="1" />
   <project path="tools/idea" name="platform/tools/idea" groups="notdefault,tools" />