dnl for each function found we get a definition in config.h
dnl of the form HAVE_FUNCTION
-AC_CHECK_FUNCS(tzset fsync mbstowcs opendir readdir chdir chroot getuid setlocale strerror snprintf vsnprintf fpclass class fp_class isnan memmove strchr mktime getrusage gettimeofday)
+AC_CHECK_FUNCS(tzset fsync mbstowcs opendir readdir chdir chroot getuid setlocale strerror snprintf vsnprintf vasprintf fpclass class fp_class isnan memmove strchr mktime getrusage gettimeofday)
AC_FUNC_STRERROR_R