Fix two inconsistencies in MUSL .deb package naming:
1. Change dpkg_arch for aarch64-unknown-linux-musl from `arm64` to
`musl-linux-arm64` to match the convention used by other MUSL targets.
2. Change the DPKG_BASENAME case pattern from `*-musl)` to `*-musl*)`
so it also matches `musleabihf`, giving the arm target the `bat-musl`
prefix like all other MUSL packages.
After this fix, all MUSL .deb packages follow the consistent pattern:
`bat-musl_VERSION_musl-linux-ARCH.deb`
Closes#3482
Matt Van Horn
618d7340bb