re_compile_internal
ret = re_compile_internal (bufp, pattern, length, re_syntax_options);
static reg_errcode_t re_compile_internal (regex_t *preg, const char * pattern,
ret = re_compile_internal (preg, pattern, strlen (pattern), syntax);
ret = re_compile_internal (&re_comp_buf, s, strlen (s), re_syntax_options);