RFR: 8292628: x86: Improve handling of constants in trigonometric stubs [v2]

[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:

  StubRoutines cleanup

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9923/files
  - new: https://git.openjdk.org/jdk/pull/9923/files/2141c1e4..98bfa9ec

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9923&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9923&range=00-01

  Stats: 90 lines in 3 files changed: 0 ins; 90 del; 0 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