RFR: 8296115: Allow for compiling the JDK with strict standards conformance [v4]

[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 seven additional commits since the last revision:

 - Export not required
 - Merge remote-tracking branch 'upstream/master' into permissive
 - 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/de41a935..1dd9765c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10912&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10912&range=02-03

  Stats: 1572 lines in 69 files changed: 254 ins; 1196 del; 122 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