RFR: 6506405: Math.abs(float) is slow [v3]

[Brian Burkhalter]

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

Brian Burkhalter has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  6506405: Add comments, use new consts for masking

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4711/files
  - new: https://git.openjdk.java.net/jdk/pull/4711/files/ba950f60..174c8293

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4711&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4711&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 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