Revert "AX_LUA: fix initialization of ac_cv_header_lua_h."

This reverts commit 825427776a2a1223b64c29c9a458ee31874a8e82.

Conflicts:
	NEWS
Merge pull request #8 from tprk77/revert-8254277

AX_LUA: revert "fix initialization of ac_cv_header_lua_h."

Further details are at <http://savannah.gnu.org/patch/?8505#comment3>.