RFR: 8277868: Use Comparable.compare() instead of surrogate code

[Сергей Цыпанов]

Instead of something like

long x;
long y;
return (x < y) ? -1 : ((x == y) ? 0 : 1);

we can use `return Long.compare(x, y);`

All replacements are done with IDE.

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Commit messages:
 - 8277868: Use Comparable.compare() instead of surrogate code

Changes: https://git.openjdk.java.net/jdk/pull/6575/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6575&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8277868
  Stats: 70 lines in 12 files changed: 2 ins; 44 del; 24 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6575.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6575/head:pull/6575

PR: https://git.openjdk.java.net/jdk/pull/6575