[jdk11u-dev] RFR: 8065704: Set LC_ALL=C for all relevant commands in the build system

[Vladimir Kempik]

Please review this backport to jdk11u-dev.
This is needed to fix JDK-8278762 which was introduced by backport of JDK-8267246.
It will set LC_ALL=C for all cases now and make result to be 6.25 (instead of 6,25) always, not depending on user's locale setting.
The backport wasn't clean, 3 pieces of compare.sh patch weren't needed and small context code difference in other two chunks.

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Commit messages:
 - 8065704: Set LC_ALL=C for all relevant commands in the build system

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/717/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=717&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8065704
  Stats: 30 lines in 8 files changed: 12 ins; 0 del; 18 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/717.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/717/head:pull/717

PR: https://git.openjdk.java.net/jdk11u-dev/pull/717