They have been maintained until now in order to support distros using
older versions of `snapd` that do not support store- or user-defined
aliases, but since all supported distros now seem to be using recent
enough `snapd` releases, we can drop the aliases at last.
Set LLVM_TARGETS_TO_BUILD to only include supported architectures
This ensures that the LLVM build does not support architectures that are
not supported by LDC itself, and brings the snap package closer in line
with the upstream LDC binary builds. It should also reduce the overall
size of the package.
This should help deal with the LDC 1.9.0 build issues that are seeing
'file truncated' errors crop up (probably because of race conditions
between make targets). Since the snapcraft cmake plugin only supports
the `make` backend, we have to create a manual `override-build` script
to run `cmake`, `ninja` and `ctest`.
This should ensure that both 32- and 64-bit libraries are available in
the snap package, whatever the target architecture of the build. With
various issues addressed since the last time we tried this, it seems
worth repeating the attempt.
`ldc2.conf` has been updated to handle all possible expected library
paths: `lib` for native, `lib32` for 32-bit libraries in a 64-bit build,
and `lib64` for 64-bit libraries in a 32-bit build.
