To address the reported issue https://github.com/llvm/llvm-project/issues/59315, this patch updates `PPCTTIImpl::supportsTailCallFor()` in following aspects:
(1) Add check logic for non-64BitELFABI sub-targets. This part of logic is missing from previous fix D131953, and caused the issue.
(2) Disable tailcall generation when longcall feature is turned on.
(3) Reuse `mayBeEmittedAsTailCall()` from TLI to check for 64BitELFABI sub-targets.
(4) Add asserts requirement for the test case.