Enable OracleAccess on ARM64, master branch (2022.04.19.)

Elabled the build of OracleAccess on non-x86 platforms in response to ATLINFR-4507. With LCG_101arm_3 that library can be built just fine. And it is needed by some of the Athena jobs.

I decided to do it "properly" like this, since we use the master branch's code in our current nightlies already. So instead of patching things in atlas/atlasexternals it seemed to make more sense to fix things at their source. 😉