System: Add missing include

src/ruc/meta/types.h

@@ -23,3 +23,7 @@ inline bool is(U* input)
 {
 	return input && is<T>(*input);
 }
+
+// References:
+// - serenity/AK/TypeCasts.h
+// - serenity/Userland/Libraries/LibJS/AST.h

src/ruc/system.cpp

@@ -1,3 +1,4 @@
+#include <algorithm>  // std::sort, std::unique
 #include <cerrno>     // errno, EAGAIN, EINTR
 #include <cstddef>    // size_t
 #include <cstdio>     // perror, ssize_t