* Make use of `PackageUpdater` more efficient by avoiding multiple calls of
`addDepsAndProvidesFromOtherPackage`
* Fix leaving old provides in the database by splitting the update via new
`beginUpdate()` and `endUpdate()` functions
When adding a new database when reloading the config at runtime the
architecture must be passed when creating the database. Otherwise we end up
with the new database sharing the internal storage with the x86_64 database
which leads to very confusing behavior.
* Only lock the config for writing the reloading the config file
* Make sure all write operations to the database acquire an "update mutex"
to ensure only one write operation happens at a time
* Do *not* acquire any additional locks when reading from a database as it
should be safe to do so even when a write operation happens because
* LMDB read and write transactions can happen at the same time
* The package cache has its own mutex anyways
* Write ops to the package cache try to lock the "update mutex" to
prevent writing "old" data to the cache during updates
* Make "lastUpdate" atomic to avoid locking the config when accessing it
It is about
```
return result_type{ storageEntry.id, storageEntry.ref.relatedStorage };
```
but it isn't clear why the compiler thinks there's a problem.
Martchus