fallback to generator expression for protoc target

Author: RayeS2070

cmake/SetupProtobuf.cmake

@@ -60,7 +60,11 @@ if(NOT USERVER_FORCE_DOWNLOAD_PROTOBUF)
 
     if(Protobuf_FOUND)
         _userver_set_protobuf_version_category()
-        set(PROTOBUF_PROTOC $<TARGET_FILE:protobuf::protoc>)
+        if (TARGET protobuf::protoc)
+            set(PROTOBUF_PROTOC $<TARGET_FILE:protobuf::protoc>)
+        else()
+            set(PROTOBUF_PROTOC "${Protobuf_PROTOC_EXECUTABLE}")
+        endif()
         return()
     endif()
 endif()