Only include <format> if __cpp_lib_format is definedHEADdev

With C++ 17, MSVC evaluates __has_include(<format>) to true and does not
prevent inclusion of the <format> header. This leads to build warnings:

    STL4038: The contents of <format> are available only with C++20 or
    later.

Because of similar issues with GCC, we stopped using __has_include for
feature detection, and instead require C++20 <version> to be available,
even in C++17 builds, cf. b2ed29b8d9b33dcece83000aee28073dd27f1cd9.

Since we include <version> centrally these days, we can just use the
feature test macro, __cpp_lib_format, directly.

Amends ffac33964d51971a1c1f61308b6f0a60a4133296.

Task-number: QTBUG-104654
Pick-to: 6.8
Change-Id: Ie923af92a7f8ab19cbd9cac9307f3f2e9a72e316
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

0 files changed, 0 insertions, 0 deletions