AC_CHECK_FUNCS([canonicalize_file_name realpath getrusage getuid \
getgid poll pread64 sbrk setpgid setpgrp setsid \
sigaction sigprocmask sigsetmask socketpair syscall \
- ttrace wborder setlocale iconvlist libiconvlist])
+ ttrace wborder setlocale iconvlist libiconvlist btowc])
AM_LANGINFO_CODESET
# Check the return and argument types of ptrace. No canned test for