Add a system_modules defn for core.current.stubs

The build system uses core-system-modules with
core.current.stubs, which is incorrect because
core-system-modules contains the implementation
code.

Test: EXPERIMENTAL_JAVA_LANGUAGE_LEVEL_9=true m droid java cts tests docs
Change-Id: Ibda795e829acee2d44ea1fcc2a07951443727cdf
1 file changed