ac_check_define.m4: AC_REQUIRE([AC_PROG_CPP]) -- fixes bug #5234.

acinclude/ac_check_define.m4

@@ -1,4 +1,4 @@
-AC_DEFUN([AC_CHECK_DEFINE],[dnl
+AC_DEFUN([AC_CHECK_DEFINE],[AC_REQUIRE([AC_PROG_CPP])dnl
   AC_CACHE_CHECK(for $1 in $2, ac_cv_define_$1,
     AC_EGREP_CPP([YES_IS_DEFINED], [
 #include <$2>