You can already control the cache size in libtorrent 1.2.x so it doesn't make sense to implement this limit for all use cases. Also there are some downsides to using working set size to limit memory usage such as unresponsive GUI when limit gets hit.
PR #17275.
msys2 was reporting the following error:
```
D:/a/qbittorent_msys2/qbittorent_msys2/src/qBittorrent/src/app/application.cpp: In member function 'void Application::applyMemoryWorkingSetLimit()':
D:/a/qbittorent_msys2/qbittorent_msys2/src/qBittorrent/src/app/application.cpp:777:36: error: no matching function for call to 'min(unsigned int, long unsigned int)'
777 | const SIZE_T minSize = std::min((64 * MiB), (maxSize / 2));
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
```
Some linux distros seem to alter TMPDIR environment variable and
therefore hamper qbt ability to find the lock files. So use config
folder instead of TMPDIR folder to create/locate the lock files.
Note that this change will also make qbt become one instance per-user
instead of one instance per-system.
Closes#15646.
Now the comparison function/class should be constructed before usage.
This change also make it easier to plug in into various containers which
will require a compare function type (such as std::set).
Define "torrent ID" concept, which is either a SHA1 hash for torrents of version 1,
or a SHA256 hash (truncated to SHA1 hash length) for torrents of version 2.
Add support for native libtorrent2 info hashes.
Originally, it was just a wrapper for libtorrent::torrent_handle class, so it mimicked its name.
It was then transformed into a more complex aggregate, but the name was retained (just by inertia).
Unlike libtorrent::torrent_handle class in whose name "handle" means the pattern used,
it does not matter for qBittorrent classes and just eats up space in the source code.
The basic idea is we create a version header template at
"src/base/version.h.in" and the build systems are expected to replace
strings that are enclosed with @ symbols and generate
"src/base/version.h" for other source files to consume/include.
