The constructor FColor(const FLinearColor& C) is now private since the following commit:
https://github.com/EpicGames/UnrealEngine/commit/d287c6143f0e7ac11070d05641be26f982794b79
However the following line: https://github.com/EpicGames/UnrealEngine/blob/4.11/Engine/Plugins/ScriptPlugin/Source/ScriptGeneratorPlugin/Private/LuaScriptCodeGenerator.cpp#L82
generates calls to that constructor when building and using the ScriptGeneratorPlugin.
For more details on the generated errors http://pastie.org/10849393