UnixPB: Add symlinks for libffi.so.6 on SLES12 & SLES15

[steelhead31]

Update unix playbooks for SLES12 and SLES15 to create a symlink for libffi.so.6, to the relevant installed version.

Fixes Build #1058

VPC Running at : https://ci.adoptium.net/job/VagrantPlaybookCheck/1617/

• commit message has one of the standard prefixes
• playbook changes run through VPC or QPC (if you have access)

[sxa]

LGTM, although do you know if this has to be a clause specific to s390x?
(I'm approving so this can go in regardless since we don't have any SLES on other architectures at the moment ;-) )

[steelhead31]

LGTM, although do you know if this has to be a clause specific to s390x? (I'm approving so this can go in regardless since we don't have any SLES on other architectures at the moment ;-) )

Im not entirely sure, its largely determined by how up to date the repo's are, so I went with the safest path first.. if we get a different variety of SLES, it'll probably be worth checking.

[Haroon-Khel]

LGTM