winedump, dbghelp: In .pdb files (>= VC2005), handle the case where the codeview_linetab2_file structure is not the first one.

winex11: Make sure the formats are the same instead of the depths since the bit ordering can be different.

The internal order of the depth and stencil bits is unspecified since the
format isn't lockable.

We don't just use the function for StorageImpl.

The function is not always called with a top-level storage object, and the
signature should reflect that.

Finding the parent of a node in a binary tree is a detail that should
be handled inside the function.

The directory entry should still be valid as long as it's in the tree.