avoid continuous rebuilds from LUA_API* changes

Signed-off-by: M. Liebmann <tuxcode.bbg@gmail.com>

src/gui/lua/Makefile.am

@@ -45,3 +45,19 @@ libneutrino_gui_lua_a_SOURCES = \
 	lua_threads_copy.cpp \
 	lua_threads_functions.cpp \
 	lua_video.cpp
+
+# the continuous changes of LUA_API_VERSION_* in luainstance.h
+# are not only of questionable usefulness, but they also cause
+# rebuilds all over the place, even though it is only used in
+# 2(!) source files. So split out those two definitions into an
+# autogenerated separate file, they are #if 0'ed in luainstance.h
+# already and the rest is dealt with via ccache...
+BUILT_SOURCES = lua_api_version.h
+lua_api_version.h: luainstance.h
+	@rm -f $@
+	grep '^#define.*LUA_API' $(srcdir)/luainstance.h > $@
+
+noinst_HEADERS = lua_api_version.h
+
+# so that lua_api_version.h can be found...
+AM_CPPFLAGS += -I$(builddir)

src/gui/lua/lua_misc.cpp

@@ -36,6 +36,9 @@
 #include "luainstance.h"
 #include "lua_misc.h"
 
+/* autogenerated from luainstance.h */
+#include "lua_api_version.h"
+
 extern CVolume* g_volume;
 
 CLuaInstMisc* CLuaInstMisc::getInstance()

src/gui/lua/luainstance.cpp

@@ -49,6 +49,9 @@
 #include "lua_threads.h"
 #include "lua_video.h"
 
+/* autogenerated from luainstance.h */
+#include "lua_api_version.h"
+
 extern CPictureViewer * g_PicViewer;
 extern cVideo         * videoDecoder;
 

src/gui/lua/luainstance.h

@@ -31,8 +31,10 @@ extern "C" {
 
 #include "luainstance_helpers.h"
 
+#if 0
 #define LUA_API_VERSION_MAJOR 1
 #define LUA_API_VERSION_MINOR 35
+#endif
 
 void LuaInstRegisterFunctions(lua_State *L, bool fromThreads=false);