Added a workaround for an AMD driver bug where setCanvas + clear + setCanvas doesn't work.

src/modules/graphics/opengl/OpenGL.h

@@ -169,6 +169,19 @@ public:
 		int    framebufferBinds;
 	} stats;
 
+	struct Bugs
+	{
+		// On AMD's Windows (and probably Linux) drivers,
+		// glBindFramebuffer + glClear + glBindFramebuffer won't work unless
+		// there's a draw in between the glBindFramebuffer calls (or unless
+		// there's some other thing that causes the driver to avoid the buggy
+		// "fast path", e.g. if the scissor test is active and its rectangle
+		// doesn't cover the whole framebuffer).
+		// Bug observed January 2016 with multiple AMD GPUs and driver versions.
+		// https://love2d.org/forums/viewtopic.php?f=4&t=81496
+		bool clearRequiresDummyDraw;
+	} bugs;
+
 	OpenGL();
 
 	/**