Don't use uninitialized variable

[csware]

The usage of the uninitialized variable findbuf on https://github.com/git-for-windows/git/blob/master/compat/mingw.c#L858 causes undefined behavior in libgit (if if (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) { is false).

This is fixed by initializing it properly which is only present in Git for Windows but not vanilla Git.

[dscho]

The usage of the uninitialized variable findbuf on https://github.com/git-for-windows/git/blob/master/compat/mingw.c#L858 causes undefined behavior in libgit (if if (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) { is false).

Is it? I see the only user to be

 		buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes,
			findbuf.dwReserved0, file_name);

... and file_attr_to_st_mode() uses the tag parameter (i.e. the parameter as which findbuf.dwReserved0 is passed) only in this expression:

 	if ((attr & FILE_ATTRIBUTE_REPARSE_POINT) &&
 		tag == IO_REPARSE_TAG_SYMLINK) {

In other words, the tag variable is only ever used if fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT is true.

Having said that, with a more accurate commit message, I would love to merge this, as it makes it easier to reason about the correctness of the code.
I.e.

[csware]

@dscho
Updated.

[dscho]

Thank you so much, especially for your patience!