ci: Add lib-vt Android support

[elias8]

Although lib-vt can be cross-compiled for Android, Zig's build system currently makes it hard to produce a properly linked dynamic .so that loads correctly on Android devices.

Issues

1. Zig's lack of support for Android bionic libc (ziglang/zig#23906). Without this, the resulting .so lacks DT_NEEDED libc.so, causing dlopen to fail resolving __tls_get_addr at runtime.
2. Android's 16 KB page size requirement

See the attached screenshot and logs below for more details.

Solution

1. Use the Android NDK for Android-specific builds. As a workaround, you can stub a few missing C functions and get it to work without the bionic libc, but that's more of a hacky solution, and most importantly, we lose the chance of adding SIMD support that we get by using the NDK, which I think can boost the library's performance. Regarding the implementation, we would need one build package to set up the NDK and configure a few build files to load it; this is similar to the apple-sdk package.
2. This is a simple one-liner (lib.link_z_max_page_size = 16384;) fix that should be applied to Android builds.

I have a working solution (see screenshot below) after some debugging, and I'll do some cleanup, set up a new CI for Android-specific build, and open a PR if the above solution/suggestion is sound.

Issue # 1 Error Log

Invalid argument(s): Couldn't resolve native function 'ghostty_terminal_new_with_config' in 'package:libghostty/libghostty.dart' : Failed to load dynamic library 'libghostty-vt.so': Failed to load dynamic library 'libghostty-vt.so': dlopen failed: cannot locate symbol "__tls_get_addr" referenced by "/data/app/~~uIeUUFwZFxKG7BMhbpB5JQ==/com.spectre.spectre-CCrhLsW1Vw-o4wMJyEVv5w==/base.apk!/lib/x86_64/libghostty-vt.so"....

Issue # 2 Screenshot

Running `lib-vt` on Android

[rhodes-b]

For the second point is there a tracking issue for zig? I don't think the long term should be the responsibility of the application to know to pass that linker flag, the compiler should know to default to it

[elias8]

I haven't found any tracked issue on zig repo and I don't think this would be much of an issue to maintain here as well.

[rhodes-b]

I wasn't saying its a problem to have here.
My point was if android expects 16kb size then zig should know to do this automatically instead of every single zig andriod app in the world knowing they need to pass this magic linker flag

anyways I made one since I could't find it as well
https://codeberg.org/ziglang/zig/issues/31306

[elias8]

I think so too. However, I am not sure they prioritize this, given Android build system itself does not support cross-compilation. The bionic support issue has been open since last year (which is not on codeberg). Android build seems to be more manual, from what I've noticed.

[rhodes-b]

thats always going to be the case with more niche targets, as the language gets alot closer to 1.0 I think they will be taking a closer look into those targets as there is still much to do with the big 3 at the moment (those being linux, macos and windows). The creator of the bionic issue goes great work at supporting these more niche targets though so I am hopeful that it will eventually get addressed

[mitchellh]

!vouch

[mitchellh]

I support this. I don't want to create a tracking issue since there are obviously some upstream issues here but if you have workarounds for them AND you can get a CI build for them going, then I'll 100% accept it.