Otherwise the compiler will probably give us a warning that these
pragmas are unknown. By default that warning is disabled with our
own build system, but we also want to be able to link to our library
without incorporating the entire build system too.
If a function is used by a template but this template is not
instantiated, the function will still be defined in the header
of a module but it won't be callable because it is in an anonymous
namespace and thus we get a warning.
This only happens in Clang; GCC consider functions referenced from
templates as used.
fixup! Don't warn about functions not emitted
