Fix a test failure on some systems.

Taken from upstream:
https://github.com/strace/strace/commit/4377e3a1535a0ec3a42da8a1366ad6943f4efa0e

diff --git a/tests/gen_tests.in b/tests/gen_tests.in
index 4a506b94c..4fdf4722c 100644
--- a/tests/gen_tests.in
+++ b/tests/gen_tests.in
@@ -168,16 +168,16 @@ ipc_msg-Xabbrev	+ipc.sh -Xabbrev -a26
 ipc_msg-Xraw	+ipc.sh -Xraw -a16
 ipc_msg-Xverbose	+ipc.sh -Xverbose -a34
 ipc_msgbuf-Xabbrev	+ipc_msgbuf.test -Xabbrev
-ipc_msgbuf-Xraw	+ipc_msgbuf.test -Xraw -a22
+ipc_msgbuf-Xraw	+ipc_msgbuf.test -Xraw -a20
 ipc_msgbuf-Xverbose	+ipc_msgbuf.test -Xverbose
 ipc_sem	+ipc.sh -a29
 ipc_sem-Xabbrev	+ipc.sh -Xabbrev -a29
 ipc_sem-Xraw	+ipc.sh -Xraw -a19
 ipc_sem-Xverbose	+ipc.sh -Xverbose -a36
-ipc_shm	+ipc.sh -a29
-ipc_shm-Xabbrev	+ipc.sh -Xabbrev -a29
+ipc_shm	+ipc.sh -a26
+ipc_shm-Xabbrev	+ipc.sh -Xabbrev -a26
 ipc_shm-Xraw	+ipc.sh -Xraw -a19
-ipc_shm-Xverbose	+ipc.sh -Xverbose -a36
+ipc_shm-Xverbose	+ipc.sh -Xverbose -a34
 kcmp	-a22
 kcmp-y	-a22 -y -e trace=kcmp
 kern_features -a16
