Move multidex support library

Multidex is being moved from frameworks/support/multidex to
frameworks/multidex.

GMS Core will be using the multidex library and has gotten special
approval to use the unreleased multidex library (i.e., guinea pig).

Bug: 10674263
Change-Id: Iff895425d4d7b2278641cbe147bd35d0788cadee
1 file changed