Fix missing includes in fmt.cc (#3994)

This causes duplicated std definitions in the fmt module

include/fmt/base.h

@@ -8,9 +8,12 @@
 #ifndef FMT_BASE_H_
 #define FMT_BASE_H_
 
-#include <limits.h>  // CHAR_BIT
-#include <stdio.h>   // FILE
-#include <string.h>  // strlen
+// c headers are preferable for performance reasons
+#ifndef FMT_MODULE
+#  include <limits.h>  // CHAR_BIT
+#  include <stdio.h>   // FILE
+#  include <string.h>  // strlen
+#endif
 
 #ifndef FMT_IMPORT_STD
 // <cstddef> is also included transitively from <type_traits>.

include/fmt/chrono.h

@@ -2144,8 +2144,7 @@ struct formatter<day, Char> : private formatter<std::tm, Char> {
     if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
     detail::get_locale loc(false, ctx.locale());
     auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
-    w.on_day_of_month(detail::numeric_system::standard,
-                      detail::pad_type::zero);
+    w.on_day_of_month(detail::numeric_system::standard, detail::pad_type::zero);
     return w.out();
   }
 };