RFR: 8256857: ARM32 builds broken after JDK-8254231 [v3]

[Aleksey Shipilev]

> Foreign linker broke ARM32 builds. This change stubs out the new entry points, without implementing the actual support yet.
> 
> Additional testing:
>  - [x] Linux arm fastdebug cross-compilation

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Merge branch 'master' into JDK-8256857-arm-foreign
 - Use nullptr instead
 - Add debug.hpp include as well
 - 8256857: ARM32 builds broken after JDK-8254231
 - 8256857: ARM32 builds broken after JDK-8254231

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1383/files
  - new: https://git.openjdk.java.net/jdk/pull/1383/files/01918d87..ff639741

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1383&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1383&range=01-02

  Stats: 220 lines in 14 files changed: 196 ins; 14 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1383.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1383/head:pull/1383

PR: https://git.openjdk.java.net/jdk/pull/1383