This changes Dumper.writeNode to spawn loader goroutines as needed
instead of as a pool. The code is shorter, fewer goroutines are spawned
for small files, and crash dumps (also for unrelated errors) should be
smaller.
It was only used in two places:
- stats: apparently as a minor performance optimization, which is
unlikely to be important
- find: filtered directories would be ignored. However, this
optimization missed that it is possible that two directories have the
exact same content. Such directories would be incorrectly ignored too.
Example:
```
mkdir test test/a test/b
restic backup test
restic find latest test/b
-> incorrectly does not return anything
```
Thus, remove the functionality as it's apparently too complex to use
correctly.
The old version was taken from an MPL-licensed library. This is a
cleanroom implementation. The code is shorter and it's now explicit that
only Linux ACLs are supported.
TestRepository and its variants always returned no-op cleanup functions.
If they ever do need to do cleanup, using testing.T.Cleanup is easier
than passing these functions around.
The ioutil functions are deprecated since Go 1.17 and only wrap another
library function. Thus directly call the underlying function.
This commit only mechanically replaces the function calls.
Package internal/dump has been reworked so its API consists of a single
type Dumper that handles tar and zip formats. Tree loading and node
writing happen concurrently.
The file permissions included a go specific directory bit which
accidentially forced the usage of the GNU header format. This leads
to problems with 7zip on Windows or when extended attributes are
used.
