The module std does not provide c-types in the global namespace. This
means all these types need to be fully qualified. This is a first step
to convert them by using sed.
Since this is an automated conversion other types like uint64_t are kept
as is.
Note that tests in the directory libcxx/test/std/depr/depr.c.headers
should not be converted automatically. This requires manual attention,
there some test require testing uint32_t in the global namespace. These
test should fail when using the std module, and pass when using the
std.compat module.
A similar issue occurs with atomic, atomic_uint32_t is specified as
using atomic_uint32_t = atomic<uint32_t>; // freestanding
So here too we need to keep the name in the global namespace in the
tests.
Comments are not really required, but since the conversion will be quite some work I prefer to make no exception for the comments.