dnl Check for usual libc functions
AC_CHECK_FUNCS([daemon fcntl fdopendir fstatvfs fork getenv getpwuid_r gettimeofday if_nameindex if_nametoindex isatty lstat memalign mmap openat pread posix_fadvise posix_madvise posix_memalign setlocale stricmp strnicmp uselocale])
-AC_REPLACE_FUNCS([asprintf atof atoll dirfd flockfile fsync getcwd getdelim getpid gmtime_r lldiv localtime_r nrand48 rewind setenv strcasecmp strcasestr strdup strlcpy strncasecmp strndup strnlen strsep strtof strtok_r strtoll swab tdestroy vasprintf])
+AC_REPLACE_FUNCS([asprintf atof atoll dirfd flockfile fsync getdelim getpid gmtime_r lldiv localtime_r nrand48 rewind setenv strcasecmp strcasestr strdup strlcpy strncasecmp strndup strnlen strsep strtof strtok_r strtoll swab tdestroy vasprintf])
AC_CHECK_FUNCS(fdatasync,,
[AC_DEFINE(fdatasync, fsync, [Alias fdatasync() to fsync() if missing.])
])