Changes how dependency options are handled and moves them out of
`CMakeLists.txt`.
Major changes:
1. The static default now takes `TARGET_SUPPORTS_SHARED_LIBS` into account
2. The `DIST` setting no longer affects the static default.
3. The static option is now visible for system dependencies as well.
(it was previously hidden by `cmake_dependent_option`).
4. The auto-detection mechanism for `libfmt` and `SDL_image` only
applies if the setting has not been set.
5. SDL2 on Android is now also linked statically,
resulting in a 1.1 MiB smaller APK.
When using non-system dependencies, the default should always be static,
as there are 2 main use cases for these:
1. Dependencies that we must currently vendor because our forks have
significant changes that are not yet merged/released upstream.
2. Platforms that have no system packages, such as Android and iOS.
In both cases, static linking is the most appropriate default.
1. Organize and comment on various options that we set.
2. Disable all system dependencies explicitly instead of relying on
auto-detection for some of them.
Previously, only the translations were copied for Android at build time.
The other assets were copied only at configure time.
Replaces Android-specific handling with a general mechanism to override
the build-time assets directory.
libmpq is a much simpler alternative to StormLib for reading MPQ archives.
We use our own fork of libmpq: https://github.com/diasurgical/libmpq
Impact:
* DevilutionX is now a lot more portable. Unlike StormLib, libmpq only
needs platform-specific code for Windows.
* Locks around file access **removed** (instead we duplicate the file descriptor for streamed audio only).
* RAM usage is **300 KiB** lower than StormLib.
* Stripped release linux_x86_64 binary is **32 KiB** smaller.
* Amiga build now hangs instead of crashing.
Gleb Mazovetskiy
Anders Jenbo
staphen