target/ppc: check tb_env != 0 before printing TBU/TBL/DECR

When using "-machine none", env->tb_env is not allocated, causing the
segmentation fault reported in issue #85 (launchpad bug #811683). To
avoid this problem, check if the pointer != NULL before calling the
methods to print TBU/TBL/DECR.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/85
Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220714172343.80539-1-matheus.ferst@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
2 files changed