[jdk13u-dev] RFR: 8233880: Support compilers with multi-digit major version numbers

[Olga Mikhaltsova]

I'd like to backport JDK-8233880 to jdk13u for parity with jdk11u.
The original patch applied cleanly.
Checked this configure warning fix manually on Ubuntu 20.04 with gcc 10.2.0.

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Commit messages:
 - Backport 7dafe378d3b4fbbb39d1bbfdb50cc655ebf633bd

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/137/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=137&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8233880
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/137.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/137/head:pull/137

PR: https://git.openjdk.java.net/jdk13u-dev/pull/137