RFR: 8286825: Linker naming cleanup [v2]

[Jorn Vernee]

> This patch is a batch naming cleanup for the foreign linker implementation.
> 
> The naming changes are as follows:
> 
>   - ProgrammableInvoker -> DowncallLinker
>   - ProgrammableUpcallHandler -> UpcallLinker
>   - 'native invoker' -> 'downcall stub'
>   - 'optimzed entry blob' -> 'upcall stub'
>   - OptimizedEntryBlob -> UpcallStub
>   - optimized_entry_frame -> upcall_stub_frame
> 
> Then renaming of some hotspot files:
> 
>   - universalNativeInvoker* -> downcallLinker*
>   - universalUpcallHandler* -> upcallLinker*
>   - foreign_globals* -> foreignGlobals* (to match existing convention)
>   
> Method, field, and other variable names are also adjusted accordingly.

Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:

  Comments + cleanup

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8777/files
  - new: https://git.openjdk.java.net/jdk/pull/8777/files/7b0e3a88..b362a822

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8777&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8777&range=00-01

  Stats: 14 lines in 3 files changed: 0 ins; 0 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8777.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8777/head:pull/8777

PR: https://git.openjdk.java.net/jdk/pull/8777