libllvm does not create a native llvm-config

[vishalbiswas]

Cross compiling llvm builds a native (host=build) version of llvm-config as a make step. But in termux, this is not the case. The native llvm-config is built for target host.
The native build takes place in $TERMUX_PKG_BUILDDIR/NATIVE. I was unable to find the root cause, but, the native build also uses $TERMUX_STANDALONE_TOOLCHAIN/bin/clang++. I suspect that this may be a bug in the cross compilation mechanism of cmake itself.

This is required to build rustc and other packages dependent on llvm-config.

[ghost]

Implemented in #917.

[vishalbiswas]

This was kept open because the underlying bug which caused libllvm to not create a host=gnueabi/target=androideabi llvm-config was never fixed. It was just sidestepped.

[stale]

This issue/PR has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[truboxl]

Relevant files to look at: https://github.com/llvm/llvm-project/tree/main/llvm/tools/llvm-config

I dive a little bit and I wonder if it has always been this way (llvm-config will be built for Target not Build)
Target = Android
Build = Linux

For our use case if we want to have cross llvm-config that can run on Build, maybe we should just host build manually ourselves.
Need to track down where the Android variables went to...