Kill off some usages of c_str.

Also changes some function params, but this is ok.
Some simplifications were also able to be made (ie. killing off strcmps with ==, etc).

Source/Core/VideoBackends/D3D/VideoBackend.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <string>
 #include "VideoCommon/VideoBackendBase.h"
 
 namespace DX11
@@ -18,7 +19,7 @@ class VideoBackend : public VideoBackendHardware
 
 	void ShowConfig(void* parent);
 
-	void UpdateFPSDisplay(const char*);
+	void UpdateFPSDisplay(const std::string&);
 	unsigned int PeekMessages();
 };