The previous patch left a broken `__redox__ && HAVE_GETLOCALENAME_L`
branch that referenced the non-existent relibc function `getlocalename_l`,
causing the m4 build to fail with:
error: #error "Please port gnulib getlocalename_l-unsafe.c to your platform!"
Redox's relibc has no `getlocalename_l` symbol. The patch now uses
`__redox__ && !HAVE_GETLOCALENAME_L` and returns "C" (matching
the existing `__ANDROID__` branch behaviour for unknown locales),
so the build no longer hits the gnulib #error.
vasilito