Avoid the warnings about the redefinition of LUA_USE_DLOPEN, when BR2_PACKAGE_LUA_INTERPRETER_READLINE is set

See src/luaconf.h lines 36-40

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Acked-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/lua/lua.mk

@@ -9,7 +9,7 @@ LUA_SITE = http://www.lua.org/ftp
 LUA_INSTALL_STAGING = YES
 
 ifeq ($(BR2_PACKAGE_LUA_SHARED_LIBRARY),y)
-	LUA_MYCFLAGS += -fPIC -DLUA_USE_DLOPEN
+	LUA_MYCFLAGS += -fPIC
 	LUA_MYLIBS += -ldl
 endif
 
@@ -18,7 +18,7 @@ ifeq ($(BR2_PACKAGE_LUA_INTERPRETER_READLINE),y)
 	LUA_MYLIBS += -lreadline -lhistory -lncurses
 	LUA_MYCFLAGS += -DLUA_USE_LINUX
 else
-	LUA_MYCFLAGS += -DLUA_USE_POSIX
+	LUA_MYCFLAGS += -DLUA_USE_POSIX -DLUA_USE_DLOPEN
 endif
 
 HOST_LUA_DEPENDENCIES =