RFR: 8292267: Clean up synchronizer.hpp [v2]

[Ioi Lam]

> Fix two problems with synchronizer.hpp:
> 
> - It's unnecessarily included in two popular headers: monitorChunk.hpp and frame_<cpu\>.hpp. The latter is most problematic because it includes synchronizer.hpp in the middle of a class declaration!
> - synchronizer.hpp includes linkedlist.hpp. This can be avoid by moving the definition of Synchronizer::PtrList into synchronizer.cpp.
> 
> These headers are included much less after this PR (out of ~1000 hotspot .o files)
> 
> 
> linkedlist.hpp    857 -> 101
> synchronizer.hpp  848 -> 122
> resourceHash.hpp  850 -> 270

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  @dcubed-ojdk review comments - reorder class forward declarations

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9849/files
  - new: https://git.openjdk.org/jdk/pull/9849/files/9b372650..f2dfac39

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9849&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9849&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/9849.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9849/head:pull/9849

PR: https://git.openjdk.org/jdk/pull/9849