RFR: 8256857: ARM32 builds broken after JDK-8254231 [v2]

[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 incrementally with one additional commit since the last revision:

  Use nullptr instead

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1383/files
  - new: https://git.openjdk.java.net/jdk/pull/1383/files/d20a6624..01918d87

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1383&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1383&range=00-01

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