RFR: 8263718: unused-result warning happens at os_linux.cpp [v2]

[Yasumasa Suenaga]

> I tried to build OpenJDK with g++-10.2.1_pre1-r3 on Alpine Linux 3.13.2, but I saw following warning:
> 
> 
>   668 | alloca(((pid ^ counter++) & 7) * 128);
>       | ^
> cc1plus: all warnings being treated as errors

Yasumasa Suenaga has updated the pull request incrementally with one additional commit since the last revision:

  Remove alloca() from some platforms

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3042/files
  - new: https://git.openjdk.java.net/jdk/pull/3042/files/006cf7d1..4485a021

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3042&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3042&range=00-01

  Stats: 35 lines in 5 files changed: 3 ins; 27 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3042.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3042/head:pull/3042

PR: https://git.openjdk.java.net/jdk/pull/3042