Remove leftover usage of the __std_stream header (#3663)
2dd4fa8742fdac36468f8d removed all usage of __std_stream because
it is no longer available with clang v17. That commit missed one place
where the header was still used (only used when building with -DFMT_MODULE=ON).
Remove it there too.
See #3654
diff --git a/src/fmt.cc b/src/fmt.cc
index a02167c..6638bb4 100644
--- a/src/fmt.cc
+++ b/src/fmt.cc
@@ -63,8 +63,6 @@
# if defined(__GLIBCXX__)
# include <ext/stdio_filebuf.h>
# include <ext/stdio_sync_filebuf.h>
-# elif defined(_LIBCPP_VERSION)
-# include <__std_stream>
# endif
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
