Meed to touch jdt core after change in compiler.tool.
See explanation in bug 560772 comment 10.

Change-Id: I918cca8e57dd750d47e2b391f03de3353f5f2f32
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.core/+/180805
Tested-by: JDT Bot <jdt-bot@eclipse.org>