[clang] [Clang][Driver] Skip empty strings in getAArch64MultilibFlags (PR #97827)

[Peter Smith via cfe-commits]

https://github.com/smithp35 commented:

A couple of comments on the test, but otherwise from the Arm and AArch64 feature modelling this looks good to me. I agree that we are not losing any useful functionality by omitting implicit flags that have no command line value.

https://github.com/llvm/llvm-project/pull/97827