[r16-4349 Regression] FAIL: 29_atomics/atomic_ref/float.cc -std=gnu++26 execution test on Linux/x86_64

[Jiang, Haochen]

On Linux/x86_64,

90dde804626f1344f0d63827709406b135433272 is the first bad commit
commit 90dde804626f1344f0d63827709406b135433272
Author: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Date:   Mon Dec 9 01:32:27 2024 +0100

    libstdc++: Handle cv-qualified types in atomic and atomic_ref [PR115402]

caused

FAIL: 29_atomics/atomic_ref/float.cc  -std=gnu++20 execution test
FAIL: 29_atomics/atomic_ref/float.cc  -std=gnu++26 execution test

with GCC configured with

../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r16-4349/usr --enable-clocale=gnu --with-system-zlib --with-demangler-in-ld --with-fpmath=sse --enable-languages=c,c++,fortran --enable-cet --without-isl --enable-libmpx x86_64-linux --disable-bootstrap

To reproduce:

$ cd {build_dir}/x86_64-linux/libstdc++-v3/testsuite && make check RUNTESTFLAGS="conformance.exp=29_atomics/atomic_ref/float.cc --target_board='unix{-m32}'"
$ cd {build_dir}/x86_64-linux/libstdc++-v3/testsuite && make check RUNTESTFLAGS="conformance.exp=29_atomics/atomic_ref/float.cc --target_board='unix{-m32\ -march=cascadelake}'"

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