Checksums: no 64-bit x86 checksum for the P16 version, 32-bit checksum inserted by mistake

[Vultaire]

In issue #149, a bug was raised re: not having a checksum for the P16 sas3ircu binary.

This was resolved, but I think the fix may have been incorrect. The checksum inserted was for the x86 32-bit version, and that was put in an entry intended for the x86 64-bit version. Indeed, I cannot install the 64-bit version of the binary due to this and had to fall back to the 32-bit version.

I think this may also be related to the charm documentation on charmhub, where the example given for sas3ircu refers to sas3ircu_linux_x86_rel/sas3ircu rather than sas3ircu_linux_x64_rel/sas3ircu.