Fix for Ubuntu.

CMakeLists.txt

@@ -572,9 +572,9 @@ if(ENABLE_TAUCS)
 endif(ENABLE_TAUCS)
 
 if(ENABLE_LUA)
-  find_library(LUA_LIB lua PATH_SUFFIXES lib)
+  find_library(LUA_LIB NAMES lua lua50 lua5.1 PATH_SUFFIXES lib)
   if(LUA_LIB)
-    find_path(LUA_INC "lua.h" PATH_SUFFIXES lua5.1 src include)
+    find_path(LUA_INC "lua.h" PATH_SUFFIXES src include lua5.1)
     if(LUA_INC)
       set_config_option(HAVE_LUA "Lua")
       list(APPEND EXTERNAL_LIBRARIES ${LUA_LIB})