[compiler-rt] [lsan] Use VReport if not REGISTERS_AVAILABLE (PR #116555)

[Vitaly Buka via llvm-commits]

vitalybuka wrote:

> I made changes to this function recently. I will try to reproduce and understand the cause.

This is from #112609

Other than Report #112609 is NFC. Before the patch we returned earlier after failed registry search.
So I confirm that this is not caused by LSAN regression, and safe to land.

https://github.com/llvm/llvm-project/pull/116555