RFR: 8255128: linux x86 build failure with libJNIPoint.c [v2]

[Jorn Vernee]

> Add 32-bit-safe version of jlong <-> casts to libJNIPoint.c
> 
> This removes the reported warning.
> 
> Note that the _LP64 macro was not being propagated to the benchmark native libraries on Windows. The comment says that this is due to pack200, but since this has been removed [1], it seemed safe to propagate the macro now (backed up by testing).
> 
> CC'ing hotspot-runtime since I know some people there were looking forward to having this fixed.
> 
> Testing: tier1-3
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8232022

Jorn Vernee has updated the pull request incrementally with two additional commits since the last revision:

 - Collapse both _LP64 if blocks in flags-cflags.m4
 - Use jlong.h macros instead of spinning new ones

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1017/files
  - new: https://git.openjdk.java.net/jdk/pull/1017/files/18e2507d..6309e2ae

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1017&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1017&range=00-01

  Stats: 23 lines in 2 files changed: 1 ins; 12 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1017.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1017/head:pull/1017

PR: https://git.openjdk.java.net/jdk/pull/1017