test-loop-block: return -77 on skip in more places

(cherry picked from commit 81e0693)
(cherry picked from commit 1fb4673)
(cherry picked from commit 8f92f75)
(cherry picked from commit 543784e)
(cherry picked from commit 27bb6c8)
(cherry picked from commit 7b878c2)

Author: bluca

src/test/test-loop-block.c

@@ -218,15 +218,11 @@ static int run(int argc, char *argv[]) {
         dissected = dissected_image_unref(dissected);
 #endif
 
-        if (geteuid() != 0 || have_effective_cap(CAP_SYS_ADMIN) <= 0) {
-                log_tests_skipped("not running privileged");
-                return 0;
-        }
+        if (geteuid() != 0 || have_effective_cap(CAP_SYS_ADMIN) <= 0)
+                return log_tests_skipped("not running privileged");
 
-        if (detect_container() > 0) {
-                log_tests_skipped("Test not supported in a container, requires udev/uevent notifications");
-                return 0;
-        }
+        if (detect_container() > 0)
+                return log_tests_skipped("Test not supported in a container, requires udev/uevent notifications");
 
         assert_se(loop_device_make(fd, O_RDWR, 0, UINT64_MAX, 0, LO_FLAGS_PARTSCAN, LOCK_EX, &loop) >= 0);