Merge topic 'lang-std-levels'

80a5a86514 GNU: Fix detection of C++ 11 mode in GCC 4.{4,5,6}
c9cc3dc646 PGI: Fix detection of C++ 14/17 modes
7f05d472a2 NVHPC: Fix detection of C++ 20 mode on NVHPC < 22.7
3587579f34 XL/XLClang: Fix detection of C++ 14 mode on Linux
863cde8c19 Intel: Fix detection of C++ 14/17 modes on Linux/macOS
1e774a86d3 Intel: Fix detection of C++ 17/20 modes on Windows
b9d4db7098 CompilerId: Clarify C and C++ standard level detection
ae18811f2e IntelLLVM: Add C standard flags on Windows
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Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !9412