test: Always exit with 77 if we skip a test

Prep work for running the integration tests with meson, which requires
tests to exit with 77 to indicate they are skipped.

Note this only deals with the easy cases where there's only tests. The
hard ones where there's subtests of which only some are skipped are left
for another PR.

test/units/testsuite-08.sh

@@ -13,7 +13,7 @@ fi
 if [[ "$(systemctl show -P InitRDTimestampMonotonic)" -eq 0 ]]; then
     echo "systemd didn't run in the initrd, skipping the test"
     touch /skipped
-    exit 0
+    exit 77
 fi
 
 # We should've created a mount under /run in initrd (see the other half of the test)

test/units/testsuite-43.sh

@@ -8,7 +8,7 @@ set -o pipefail
 
 if [[ "$(sysctl -ne kernel.apparmor_restrict_unprivileged_userns)" -eq 1 ]]; then
     echo "Cannot create unprivileged user namespaces" >/skipped
-    exit 0
+    exit 77
 fi
 
 systemd-analyze log-level debug

test/units/testsuite-46.sh

@@ -6,7 +6,7 @@ set -o pipefail
 # Check if homectl is installed, and if it isn't bail out early instead of failing
 if ! test -x /usr/bin/homectl ; then
         echo "no homed" >/skipped
-        exit 0
+        exit 77
 fi
 
 inspect() {

test/units/testsuite-55.sh

@@ -16,7 +16,7 @@ test "$(cat /sys/fs/cgroup/init.scope/memory.high)" != "max"
 [[ "$(get_cgroup_hierarchy)" == "unified" ]] || echo "no cgroupsv2" >>/skipped
 [[ -x /usr/lib/systemd/systemd-oomd ]] || echo "no oomd" >>/skipped
 if [[ -s /skipped ]]; then
-    exit 0
+    exit 77
 fi
 
 rm -rf /run/systemd/system/testsuite-55-testbloat.service.d

test/units/testsuite-58.sh

@@ -9,7 +9,7 @@ set -o pipefail
 
 if ! command -v systemd-repart >/dev/null; then
     echo "no systemd-repart" >/skipped
-    exit 0
+    exit 77
 fi
 
 # shellcheck source=test/units/test-control.sh

test/units/testsuite-62.sh

@@ -44,12 +44,12 @@ MINOR_REQUIRED=7
 
 if [[ "$KERNEL_MAJOR" -lt $MAJOR_REQUIRED || ("$KERNEL_MAJOR" -eq $MAJOR_REQUIRED && "$KERNEL_MINOR" -lt $MINOR_REQUIRED) ]]; then
     echo "kernel is not 5.7+" >>/skipped
-    exit 0
+    exit 77
 fi
 
 if systemctl --version | grep -q -F -- "-BPF_FRAMEWORK"; then
     echo "bpf-framework is disabled" >>/skipped
-    exit 0
+    exit 77
 fi
 
 trap teardown EXIT

test/units/testsuite-72.sh

@@ -16,7 +16,7 @@ export SYSTEMD_LOG_LEVEL=debug
 
 if [[ ! -x "$SYSUPDATE" ]]; then
     echo "no systemd-sysupdate" >/skipped
-    exit 0
+    exit 77
 fi
 
 # Loopback devices may not be supported. They are used because sfdisk cannot