RFR: 6506405: Math.abs(float) is slow

[Brian Burkhalter]

Please consider this change to make the `float` and `double` versions of `java.lang.Math.abs()` branch-free.

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Commit messages:
 - 6506405: Math.abs(float) is slow

Changes: https://git.openjdk.java.net/jdk/pull/4711/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4711&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-6506405
  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4711.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4711/head:pull/4711

PR: https://git.openjdk.java.net/jdk/pull/4711