compilers: publicly export one more constant
compilers: publicly export one more constant

It is imported from a subpackage in __init__ alongside a big list of
other things which are all exported. And elsewhere, this import is
re-imported by other code. It's pretty clearly an oversight that it
didn't get added to __all__

mesonbuild/meson,mesonbuild/meson,pexip/meson,pexip/meson,pexip/meson,mesonbuild/meson,pexip/meson,pexip/meson,mesonbuild/meson,mesonbuild/meson,pexip/meson,pexip/meson,pexip/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,pexip/meson,pexip/meson