Add minijail to the manifest

BUG: 22357920
Change-Id: I8c2b7d66381717a7656b008cf379159cc2240b60

default.xml

@@ -219,6 +219,7 @@
   <project path="external/mdnsresponder" name="platform/external/mdnsresponder" groups="pdk" />
   <project path="external/mesa3d" name="platform/external/mesa3d" groups="pdk-cw-fs" />
   <project path="external/messageformat" name="platform/external/messageformat" groups="pdk-cw-fs" />
+  <project path="external/minijail" name="platform/external/minijail" />
   <project path="external/mksh" name="platform/external/mksh" groups="pdk" />
   <project path="external/mockftpserver" name="platform/external/mockftpserver" />
   <project path="external/mockito" name="platform/external/mockito" groups="pdk-cw-fs" />