mountpoint-util: assume MS_NOSYMFOLLOW is available

Since our kernel baseline is v5.10 now.

src/shared/dissect-image.c

@@ -2383,7 +2383,7 @@ int partition_pick_mount_options(
 
         case PARTITION_ESP:
         case PARTITION_XBOOTLDR:
-                flags |= MS_NOSUID|MS_NOEXEC|ms_nosymfollow_supported();
+                flags |= MS_NOSUID|MS_NOEXEC|MS_NOSYMFOLLOW;
 
                 /* The ESP might contain a pre-boot random seed. Let's make this unaccessible to regular
                  * userspace. ESP/XBOOTLDR is almost certainly VFAT, hence if we don't know assume it is. */

src/shared/mount-util.c

@@ -1951,7 +1951,7 @@ int trigger_automount_at(int dir_fd, const char *path) {
 
 unsigned long credentials_fs_mount_flags(bool ro) {
         /* A tight set of mount flags for credentials mounts */
-        return MS_NODEV|MS_NOEXEC|MS_NOSUID|ms_nosymfollow_supported()|(ro ? MS_RDONLY : 0);
+        return MS_NODEV|MS_NOEXEC|MS_NOSUID|MS_NOSYMFOLLOW|(ro ? MS_RDONLY : 0);
 }
 
 int fsmount_credentials_fs(int *ret_fsfd) {

src/shared/mount-util.h

@@ -166,7 +166,7 @@ int make_mount_point_inode_from_path(const char *source, const char *dest, mode_
 
 int trigger_automount_at(int dir_fd, const char *path);
 
-unsigned long credentials_fs_mount_flags(bool ro);
+unsigned long credentials_fs_mount_flags(bool ro) _const_;
 int fsmount_credentials_fs(int *ret_fsfd);
 int mount_credentials_fs(const char *path);