Create new mount directory /mnt/runtime/full.

This will be used for system internals to access
secondary volumes without having to bypass sdcardfs.

Bug: 121277410
Test: manual
Exempt-From-Owner-Approval: Got approval on internal master
Change-Id: I9b3e33f6c6e426e83469b8030b02d59c02183946
diff --git a/model/EmulatedVolume.h b/model/EmulatedVolume.h
index f618c55..fddfe4e 100644
--- a/model/EmulatedVolume.h
+++ b/model/EmulatedVolume.h
@@ -52,6 +52,7 @@
     std::string mFuseDefault;
     std::string mFuseRead;
     std::string mFuseWrite;
+    std::string mFuseFull;
 
     /* PID of FUSE wrapper */
     pid_t mFusePid;