RFR: 8311247: Some cpp files are compiled with -std:c11 flag

[Erik Joelsson]

On Mon, 3 Jul 2023 17:15:17 GMT, Daniel Jeliński <djelinski at openjdk.org> wrote:

> Please review this patch that configures C++ arguments on build jobs that involve compiling CPP files. As a result of this change, CPP files are compiled with `-std:c++14` command line argument instead of `-std:c11`, which is used when C++ arguments are not configured.
> While at it, I simplified the `java.security.jgss/Lib.gmk` file by moving the additional include directory to `EXTRA_HEADER_DIRS`.
> 
> This patch fixes the following clang warning:
> 
> warning: argument unused during compilation: '-std:c11'
> 
> 
> Microsoft states that [std:c++14 is the default](https://learn.microsoft.com/en-us/cpp/build/reference/std-specify-language-standard-version?view=msvc-170), so there shouldn't be any differences in produced code.
> 
> Testing:
> - verified that after the changes, all CPP files are compiled with `std:c++14` instead of `-std:c11`
> - spot-checked a few `cmdline` files that changed after this patch was applied; the `-std` change was the only difference
> - tier1-5 builds, tier1-2 tests and client libs tests continue to pass on Windows, Linux & MacOS.

I'm ok with this, but it's unfortunate that we need to repeat so much.

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Marked as reviewed by erikj (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14758#pullrequestreview-1567903887