lua: only install headers if BR2_HAVE_DEVFILES is enabled

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/lua/lua.mk

@@ -55,7 +55,7 @@ $(TARGET_DIR)/usr/bin/luac: $(STAGING_DIR)/usr/bin/luac
 
 lua-bins:	$(TARGET_DIR)/usr/bin/lua $(TARGET_DIR)/usr/bin/luac
 
-lua-libs:	$(TARGET_DIR)/usr/lib/liblua.a
+lua-libs: $(if $(BR2_HAVE_DEVFILES),$(TARGET_DIR)/usr/lib/liblua.a)
 
 lua: readline ncurses lua-bins lua-libs