Check whether a path component corresponds to a .git$SUFFIX file.
As some filesystems do special things to filenames when writing files to disk, you cannot always do a plain string comparison to verify whether a file name matches an expected path or not. This function can do the comparison for you, depending on the filesystem you're on.
the path component to check
the length of path
that is to be checked
0 in case the file does not match, a positive value if it does; -1 in case of an error