RFR: 8292628: x86: Improve handling of constants in trigonometric stubs

[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

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Commit messages:
 - tabs
 - x86: Improve handling of constants in trigonometric stubs

Changes: https://git.openjdk.org/jdk/pull/9923/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9923&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292628
  Stats: 784 lines in 12 files changed: 321 ins; 360 del; 103 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