[RISCV][CFI] add function epilogue cfi information (#110810)

This patch adds CFI instructions in the function epilogue.

Before patch:
addi sp, s0, -32
ld ra, 24(sp) # 8-byte Folded Reload
ld s

[RISCV][CFI] add function epilogue cfi information (#110810)

This patch adds CFI instructions in the function epilogue.

Before patch:
addi sp, s0, -32
ld ra, 24(sp) # 8-byte Folded Reload
ld s0, 16(sp) # 8-byte Folded Reload
ld s1, 8(sp) # 8-byte Folded Reload
addi sp, sp, 32
ret

After patch:
addi sp, s0, -32
.cfi_def_cfa sp, 32
ld ra, 24(sp) # 8-byte Folded Reload
ld s0, 16(sp) # 8-byte Folded Reload
ld s1, 8(sp) # 8-byte Folded Reload
.cfi_restore ra
.cfi_restore s0
.cfi_restore s1
addi sp, sp, 32
.cfi_def_cfa_offset 0
ret

This functionality is already present in `riscv-gcc`, but it’s not in
`clang` and this slightly impairs the `lldb` debugging experience, e.g.
backtrace.

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RISC-V: Select FCANONICALIZE (#112083)

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