Adds missing includes and gets more explicit about exceptions.

Outputs/OpenGL/ScanTarget.cpp

@@ -7,8 +7,12 @@
 //
 
 #include "ScanTarget.hpp"
+
 #include "Primitives/Rectangle.hpp"
 
+#include <cassert>
+#include <cstring>
+
 using namespace Outputs::Display::OpenGL;
 
 namespace {

Outputs/OpenGL/ScanTarget.hpp

@@ -77,7 +77,7 @@ class ScanTarget: public Outputs::Display::ScanTarget {
 		struct PointerSet {
 			// This constructor is here to appease GCC's interpretation of
 			// an ambiguity in the C++ standard; cf. https://stackoverflow.com/questions/17430377
-			PointerSet() {}
+			PointerSet() noexcept {}
 
 			// The sizes below might be less hassle as something more natural like ints,
 			// but squeezing this struct into 64 bits makes the std::atomics more likely