Use a constexpr for esm cc

components/esm/defs.hpp

@@ -85,7 +85,7 @@ bool inline operator!= (const Position& left, const Position& right) noexcept
 template <int a, int b, int c, int d>
 struct FourCC
 {
-    static const unsigned int value = (((((d << 8) | c) << 8) | b) << 8) | a;
+    static constexpr unsigned int value = (((((d << 8) | c) << 8) | b) << 8) | a;
 };
 
 enum RecNameInts