Revert "[PreISelIntrinsicLowering] Expand binary elementwise intrinsics (#193552) (#193580) (#193990)
This reverts commit a1d11348aba4b70295ef9ada4a13a722455165d3.
Two problems have been identified:
- The expansion for powi was functionally wrong - the second argument
stales scalar even when the first is a vector.
- AArch64 uses the Expand option on libcalls to select vector libcalls
in some cases. The test coverage for this uses -start-after which
happens to miss this pass.