Avoid :: and Integer allocation in API hashing

[retronym]

No description provided.

[jvican]

LGTM 👍

[jvican]

[error] /home/travis/build/sbt/zinc/internal/zinc-apiinfo/src/main/scala/xsbt/api/HashAPI.scala:148:17: not found: type IterableOnce
689[error]     val tsHash: IterableOnce[Any] = ts match {
690[error]                 ^
691[error] one error found
692[info] Compiling 10 Scala sources to /home/travis/build/sbt/zinc/internal/zinc-apiinfo/target/jvm-2.13/classes ...
693[warn] -Xfuture is deprecated: Not used since 2.13.
694[error] /home/travis/build/sbt/zinc/internal/zinc-apiinfo/src/main/scala/xsbt/api/HashAPI.scala:157:22: type mismatch;
695[error]  found   : Int
696[error]  required: IterableOnce[Any]
697[error]         unorderedHash(new HashIterator(ts.iterator))
698[error]                      ^
699[error] /home/travis/build/sbt/zinc/internal/zinc-apiinfo/src/main/scala/xsbt/api/HashAPI.scala:159:22: type mismatch;
700[error]  found   : Int
701[error]  required: IterableOnce[Any]
702[error]         unorderedHash(ts.toList.map { t =>
703[error]                      ^
704[error] /home/travis/build/sbt/zinc/internal/zinc-apiinfo/src/main/scala/xsbt/api/HashAPI.scala:166:12: type mismatch;
705[error]  found   : IterableOnce[Any]
706[error]  required: xsbt.api.HashAPI.Hash
707[error]     (which expands to)  Int
708[error]     extend(tsHash)
709[error]            ^
710[warn] one warning found
711[error] three errors found