arch-arm: Fix dangling pointer to unnamed temporary in nativetrace.cc.

Name the temporary.

Change-Id: I51d0eaa4a6759c3f288b4215db880af6135e9107
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/60409
Reviewed-by: Yu-hsin Wang <yuhsingw@google.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed