constexpr for struct

Signed-off-by: Rosen Penev <rosenp@gmail.com>

Author: neheb

src/futils.cpp

@@ -206,7 +206,7 @@ size_t base64decode(const char* in, char* out, size_t out_size) {
 
 Protocol fileProtocol(const std::string& path) {
   Protocol result = pFile;
-  const struct {
+  constexpr struct {
     std::string_view name;
     Protocol prot;
     bool isUrl;  // path.size() > name.size()

src/olympusmn_int.cpp

@@ -1360,7 +1360,7 @@ std::ostream& OlympusMakerNote::print0x0201(std::ostream& os, const Value& value
 
   // 6 numbers: 0. Make, 1. Unknown, 2. Model, 3. Sub-model, 4-5. Unknown.
   // Only the Make, Model and Sub-model are used to determine the lens model
-  static const struct {
+  static constexpr struct {
     byte val[3];
     const char* label;
   } lensTypes[] = {
@@ -1514,7 +1514,7 @@ std::ostream& OlympusMakerNote::print0x0209(std::ostream& os, const Value& value
 std::ostream& OlympusMakerNote::printEq0x0301(std::ostream& os, const Value& value, const ExifData*) {
   // 6 numbers: 0. Make, 1. Unknown, 2. Model, 3. Sub-model, 4-5. Unknown.
   // Only the Make and Model are used to determine the extender model
-  static const struct {
+  static constexpr struct {
     byte val[2];
     const char* label;
   } extenderModels[] = {