service/service: Make FunctionInfo's constructor constexpr

Allows our service function arrays to be constexpr.

src/core/hle/service/service.h

@@ -122,9 +122,6 @@ class ServiceFramework : public ServiceFrameworkBase {
 protected:
     /// Contains information about a request type which is handled by the service.
     struct FunctionInfo : FunctionInfoBase {
-        // TODO(yuriks): This function could be constexpr, but clang is the only compiler that
-        // doesn't emit an ICE or a wrong diagnostic because of the static_cast.
-
         /**
          * Constructs a FunctionInfo for a function.
          *
@@ -134,7 +131,8 @@ protected:
          *     the request
          * @param name human-friendly name for the request. Used mostly for logging purposes.
          */
-        FunctionInfo(u32 expected_header, HandlerFnP<Self> handler_callback, const char* name)
+        constexpr FunctionInfo(u32 expected_header, HandlerFnP<Self> handler_callback,
+                               const char* name)
             : FunctionInfoBase{
                   expected_header,
                   // Type-erase member function pointer by casting it down to the base class.