[libc][riscv64] Don't save/restore unsafe stack pointer in setjmp/longjmp

The $tp + ZX_TLS_UNSAFE_SP_OFFSET slot is no longer used on RISC-V.

Bug: 454394012
Depends-On: Ie9d5b1afe0e747facf72f8d4853bc675a1270659
Change-Id: I11c9922bc9ddf6c41e551d68d98cd29103e7fd86
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1420654
Commit-Queue: Roland McGrath <mcgrathr@google.com>
Fuchsia-Auto-Submit: Roland McGrath <mcgrathr@google.com>
Reviewed-by: Paul Kirth <paulkirth@google.com>
Dependencies-Satisfied: CL Deps Checker <cl-deps-checker@fuchsia-internal-service-accts.iam.gserviceaccount.com>
2 files changed