e2fsprogs: Fix some error cleanup path bugs

e2fsprogs: Fix some error cleanup path bugs

In inode_open(), if the allocation of &io fails, we go to cleanup
and dereference io to test io->name, which is a bug.

Similarly in undo_open()  if allocation of &data fails, we
go to cleanup and dereference data to test data->real.

In the test_open() case we explicitly set retval to the only
possible error return from ext2fs_get_mem(), so remove that
for tidiness.

The other changes just make make earlier returns go through
the error goto for consistency.

In many cases we returned directly from the first error, but
"goto cleanup" etc for every subsequent error.  In some
cases this leads to "impossible" tests such as:

	if (ptr)
		ext2fs_free_mem(&ptr)

on paths where ptr cannot be null because we would have
returned directly earlier, and Coverity flags this.

This isn't really indicative of an error in most cases, but
I think it can be clearer to always exit through the error goto
if it's used later in the function.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>