Work around DX90 compile error

Change-Id: I80751a41d0711c52558ba198c22d1f012998302c
diff --git a/apps/plugins/puzzles/rbcompat.h b/apps/plugins/puzzles/rbcompat.h
index 7934f5d..9069c1e 100644
--- a/apps/plugins/puzzles/rbcompat.h
+++ b/apps/plugins/puzzles/rbcompat.h
@@ -49,6 +49,7 @@
 #define getenv getenv_wrapper
 #define malloc tlsf_malloc
 #define memchr rb->memchr
+#define memswap puzzles_memswap
 #define pow pow_wrapper
 #define printf LOGF
 #define puts puts_wrapper