# C++ checks to determine what style of headers to use and# whether to use "using" clauses.AC_DEFUN(AC_CXX_HAVE_STDHEADERS, [AC_SUBST(cxx_have_stdheaders)AC_CACHE_CHECK([whether C++ supports the ISO C++ standard includes],db_cv_cxx_have_stdheaders,[AC_LANG_SAVE AC_LANG_CPLUSPLUS AC_TRY_COMPILE([#include <iostream>],[std::ostream *o; return 0;], db_cv_cxx_have_stdheaders=yes, db_cv_cxx_have_stdheaders=no) AC_LANG_RESTORE])if test "$db_cv_cxx_have_stdheaders" = yes; then	cxx_have_stdheaders="#define	HAVE_CXX_STDHEADERS 1"fi])