RFR: 8292008: Transition the JDK to the common standard of C11

[Magnus Ihse Bursie]

This patch will set C11 as the "language level" for C code in the JDK code base, similar to how we set C++14 for the C++ code.

At this point, (almost) all our compilers support C11. The "almost" here is the one exception, Visual Studio 2017. I've chosen to keep VS2017 as an accepted compiler, and if that is used, we will still build without C11 as a language level. This is a suboptimal solution however, and I think we should start thinking about removing VS2017 as a supported compiler really soon.

For further background on the switch to C11, see [JDK-8292008](https://bugs.openjdk.org/browse/JDK-8292008) and [this mail](https://mail.openjdk.org/pipermail/jdk-dev/2022-August/006826.html).

I have tested this patch with Tier 1-3 in Oracle's internal CI system.

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Commit messages:
 - 8292008: Transition the JDK to the common standard of C11

Changes: https://git.openjdk.org/jdk/pull/10077/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10077&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292008
  Stats: 15 lines in 1 file changed: 2 ins; 5 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/10077.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10077/head:pull/10077

PR: https://git.openjdk.org/jdk/pull/10077