Parameterize vformat to support custom char types

src/format.cc

@@ -8,12 +8,6 @@
 #include "fmt/format-inl.h"
 
 FMT_BEGIN_NAMESPACE
-namespace internal {
-// Force linking of inline functions into the library.
-std::string (*vformat_ref)(string_view, format_args) = vformat;
-std::wstring (*vformat_wref)(wstring_view, wformat_args) = vformat;
-}
-
 template struct internal::basic_data<void>;
 
 // Explicit instantiations for char.