Function does_file_exist

tests/functional/compact_functional_test.cc:1207–1211

#if !defined(WIN32) && !defined(_WIN32)
static bool does_file_exist(const char *filename) {
    struct stat st;
    int result = stat(filename, &st);
    return result == 0;
}
#else
static bool does_file_exist(const char *filename) {
    return GetFileAttributes(filename) != INVALID_FILE_ATTRIBUTES;