OpenBSD: Add path for Lua 5.1

Modules/FindLua51.cmake

@@ -28,7 +28,7 @@
 find_path(LUA_INCLUDE_DIR lua.h
   HINTS
     ENV LUA_DIR
-  PATH_SUFFIXES include/lua51 include/lua5.1 include/lua include
+  PATH_SUFFIXES include/lua51 include/lua5.1 include/lua-5.1 include/lua include
   PATHS
   ~/Library/Frameworks
   /Library/Frameworks