RFR: 8292628: x86: Improve handling of constants in trigonometric stubs [v3]

[Vladimir Ivanov]

> Improve how constants are handled in trigonometric stubs on x86. 
> In particular, extract shared constants into a separate file and 
> encapsulate them in MacroAssembler.
> 
> Also, some minor cleanups included. 
> 
> Testing:
>  - [x] hs-tier1 - hs-tier4
>  - [x] x86_32 build

Vladimir Ivanov has updated the pull request incrementally with one additional commit since the last revision:

  cleanups

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/9923/files
  - new: https://git.openjdk.org/jdk/pull/9923/files/98bfa9ec..e867e115

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9923&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9923&range=01-02

  Stats: 8 lines in 2 files changed: 4 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/9923.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9923/head:pull/9923

PR: https://git.openjdk.org/jdk/pull/9923