5.4 regression: C++ compilers fail to compile misc.h

[kit-ty-kate]

Yet another C++ compatibility issue (see #13777)

#=== ERROR while compiling taglib.0.3.10 ======================================#
# context              2.4.0~alpha2 | linux/x86_64 | ocaml-base-compiler.5.4.0~alpha1 | file:///home/opam/opam-repository
# path                 ~/.opam/5.4/.opam-switch/build/taglib.0.3.10
# command              ~/.opam/5.4/bin/dune build -p taglib -j 1 @install
# exit-code            1
# env-file             ~/.opam/log/taglib-14-e79929.env
# output-file          ~/.opam/log/taglib-14-e79929.out
### output ###
# File "src/dune", line 8, characters 9-21:
# 8 |   (names taglib_stubs)
#              ^^^^^^^^^^^^
# (cd _build/default/src && /usr/bin/gcc -fPIC -I/usr/include/taglib -g -I /home/opam/.opam/5.4/lib/ocaml -I /home/opam/.opam/5.4/lib/ocaml/unix -o taglib_stubs.o -c taglib_stubs.cc)
# In file included from /home/opam/.opam/5.4/lib/ocaml/caml/alloc.h:19,
#                  from taglib_stubs.cc:98:
# /home/opam/.opam/5.4/lib/ocaml/caml/misc.h:622:8: error: '_Atomic' does not name a type; did you mean 'Atom'?
#   622 | extern _Atomic uintnat caml_verb_gc;
#       |        ^~~~~~~
#       |        Atom

[dra27]

xref #13593 (which introduced the change, I think possibly solving a dependency cycle)