Configure.ac: fix check for 32 bit luac on some platforms

configure.ac

@@ -1528,7 +1528,7 @@ then
   AS_IF([test "${LUAC}" = "false"], [
     AC_MSG_ERROR([Could not find the LUA byte compiler.])
   ])
-  AS_IF([test -d "${CONTRIB_DIR}" -a -f "${CONTRIB_DIR}"/lib/liblua.a -a `echo|${LUAC} -o - -|od -j 8 -N 2 -t x2|head -n 1|cut -d' ' -f2` != 0404], [
+  AS_IF([test -d "${CONTRIB_DIR}" -a -f "${CONTRIB_DIR}"/lib/liblua.a -a `echo|${LUAC} -o - -|od -j 8 -N 2 -t x2|head -n 1|tr -s ' '|cut -d' ' -f2` != 0404], [
     AC_MSG_ERROR([You need 32-bits luac when using using lua from contrib.])
   ])
 fi