RFR: 8296115: Allow for compiling the JDK with strict standards conformance [v3]

[Julian Waters]

> [JDK-8241499](https://bugs.openjdk.org/browse/JDK-8241499) proposes to set the -permissive- flag for the Microsoft Visual C++ compiler, to enforce strict standards conformance during compilation, making native code behave more strictly. While adding it to default builds is likely not practical given how much testing is required, as an option it can prove helpful in finding areas of native code that are not conformant to the standard. Instead of applying this to just one compiler, we can also include this for every compiler that has support for such a strict mode, which this change does.

Julian Waters has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Merge remote-tracking branch 'upstream/master' into permissive
 - Merge remote-tracking branch 'upstream/master' into permissive
 - Format
 - Keep docs up to date
 - New --enable-conforming-compilation option

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10912/files
  - new: https://git.openjdk.org/jdk/pull/10912/files/7a527bc8..de41a935

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10912&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10912&range=01-02

  Stats: 11094 lines in 228 files changed: 8335 ins; 1792 del; 967 mod
  Patch: https://git.openjdk.org/jdk/pull/10912.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10912/head:pull/10912

PR: https://git.openjdk.org/jdk/pull/10912