Add scala-java8-compat to scala-library.jar
Add scala-java8-compat to scala-library.jar

When the ant build is run with `-Dscala-java8-compat.package`,
the contents of `org.scala-lang.modules:scala-java8-compat` are
spliced into `scala-library.jar`. This is handy to facilitate
downstream testing of indy lambdas, we can just use the the compiler
options `-target 1.8 -Ydelambdafy:method -Xexperimental` without
needed to add `scala-java8-compat.jar` to the compile and runtime
classpaths. (Classpath augmentation doesn't appear to be straight
forward in partest or in the community build.)

lrytz/scala,slothspot/scala,scala/scala,jvican/scala,felixmulder/scala,shimib/scala,felixmulder/scala,shimib/scala,shimib/scala,felixmulder/scala,slothspot/scala,slothspot/scala,jvican/scala,shimib/scala,martijnhoekstra/scala,lrytz/scala,lrytz/scala,jvican/scala,scala/scala,lrytz/scala,martijnhoekstra/scala,jvican/scala,slothspot/scala,scala/scala,felixmulder/scala,martijnhoekstra/scala,martijnhoekstra/scala,scala/scala,lrytz/scala,felixmulder/scala,slothspot/scala,felixmulder/scala,jvican/scala,lrytz/scala,slothspot/scala,martijnhoekstra/scala,felixmulder/scala,slothspot/scala,martijnhoekstra/scala,shimib/scala,scala/scala,scala/scala,shimib/scala,jvican/scala,jvican/scala