Fix java 9 build breakage caused by splitting core.current.stubs

Needed to change system_modules from "none" to
"art-module-public-api-stubs-system-modules" to make sure that the
java.lang classes are available.

Affected both the conscrypt and i18n module stubs.

Also needed to remove the --patch-module from core-icu4j as it
somehow prevented the external/icu4j/android_icu4j source from seeing
the classes in libcore-unsupportedappusage-annotation.

Reproduced the problem as described in test, made the change and then
verified that problem was fixed.

Test: EXPERIMENTAL_JAVA_LANGUAGE_LEVEL_9=true m javac-check
Change-Id: I3d76c9c4569a4f40c2ab804210cd24f96a515038
1 file changed