ac_cxx_have_string_push_back

If the implementation of the C++ library provides the method std::string::push_back (char), define HAVE_STRING_PUSH_BACK.

AC_DEFUN([AC_CXX_HAVE_STRING_PUSH_BACK],
[AC_CACHE_CHECK(whether the compiler has std::string::push_back (char),
ac_cv_cxx_have_string_push_back,
[AC_REQUIRE([AC_CXX_NAMESPACES])
 AC_LANG_SAVE
 AC_LANG_CPLUSPLUS
 AC_TRY_COMPILE([#include <string>
#ifdef HAVE_NAMESPACES
using namespace std;
#endif],[string message; message.push_back ('a'); return 0;],
 ac_cv_cxx_have_string_push_back=yes, ac_cv_cxx_have_string_push_back=no)
 AC_LANG_RESTORE
])
if test "$ac_cv_cxx_have_string_push_back" = yes; then
 AC_DEFINE(HAVE_STRING_PUSH_BACK,,[define if the compiler has the method
std::string::push_back (char)])
fi
])dnl