fsck: split out fsck return code definitions into a header file of its own

This way we can make use of it from other components too, such as
systemd-homed.

src/fsck/fsck.c

@@ -22,6 +22,7 @@
 #include "device-util.h"
 #include "fd-util.h"
 #include "fs-util.h"
+#include "fsck-util.h"
 #include "main-func.h"
 #include "parse-util.h"
 #include "path-util.h"
@@ -34,18 +35,6 @@
 #include "stdio-util.h"
 #include "util.h"
 
-/* exit codes as defined in fsck(8) */
-enum {
-        FSCK_SUCCESS                 = 0,
-        FSCK_ERROR_CORRECTED         = 1 << 0,
-        FSCK_SYSTEM_SHOULD_REBOOT    = 1 << 1,
-        FSCK_ERRORS_LEFT_UNCORRECTED = 1 << 2,
-        FSCK_OPERATIONAL_ERROR       = 1 << 3,
-        FSCK_USAGE_OR_SYNTAX_ERROR   = 1 << 4,
-        FSCK_USER_CANCELLED          = 1 << 5,
-        FSCK_SHARED_LIB_ERROR        = 1 << 7,
-};
-
 static bool arg_skip = false;
 static bool arg_force = false;
 static bool arg_show_progress = false;