crucible: add cleanup class

Store a function (or closure) in an instance and invoke the function
from the destructor.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

include/crucible/cleanup.h

@@ -0,0 +1,18 @@
+#ifndef CRUCIBLE_CLEANER_H
+#define CRUCIBLE_CLEANER_H
+
+#include <functional>
+
+namespace crucible {
+	using namespace std;
+
+	class Cleanup {
+		function<void()> m_cleaner;
+	public:
+		Cleanup(function<void()> func);
+		~Cleanup();
+	};
+
+}
+
+#endif // CRUCIBLE_CLEANER_H