Make the javac arguments match what is used by make, and export them
back to make. A future change will switch make to use the the
exported ones.
This makes a dx.jar compiled with soong have identical class files
as one compiled with make.
Test: manual
Change-Id: Ia5196f1f42bc564e99de22e32e72fd2930e9fbae
Add a java/config package to hold config information, and share
it with make through makevars.
Test: builds
Change-Id: I46c088bda0fe97a1823bfdd80fa692d0bf61da1b