fix: missing `PROTOBUF_EXPORT` for public symbols

PiperOrigin-RevId: 537042088

src/google/protobuf/io/strtod.h

@@ -60,12 +60,12 @@ PROTOBUF_EXPORT std::string SimpleFtoa(float value);
 
 // A locale-independent version of the standard strtod(), which always
 // uses a dot as the decimal separator.
-double NoLocaleStrtod(const char* str, char** endptr);
+PROTOBUF_EXPORT double NoLocaleStrtod(const char* str, char** endptr);
 
 // Casts a double value to a float value. If the value is outside of the
 // representable range of float, it will be converted to positive or negative
 // infinity.
-float SafeDoubleToFloat(double value);
+PROTOBUF_EXPORT float SafeDoubleToFloat(double value);
 
 }  // namespace io
 }  // namespace protobuf