Include <system_error> only on Windows to avoid Clang warning

Martchus · Martchus · commit df5e11130225 · 2025-10-08T16:27:07.000+02:00
`std::error_code` is only used in Windows-specific APIs so Clang complains
about an unused include on other platforms.
diff --git a/conversion/stringconversion.h b/conversion/stringconversion.h
@@ -15,9 +15,12 @@
 #include <sstream>
 #include <string>
 #include <string_view>
-#include <system_error>
 #include <vector>
 
+#ifdef PLATFORM_WINDOWS
+#include <system_error>
+#endif
+
 // configure use of ranges and concepts
 #if __cplusplus >= 201709
 #include <version>
