Don't allocate closure in List.hashCode.
Don't allocate closure in List.hashCode.

Provided specialized version of hashing algorithm
for List that does not allocate the closure.

This saves us 124k closures allocated in a compiler
when compiling `Vector.scala` from std library.
That's aroudn 5% of all closures allocated for that
compiler run.

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