swaponoff: add uuid/label support. By Natanael Copa

function                                             old     new   delta
swap_enable_disable                                  130     150     +20
resolve_mount_spec                                    76      96     +20
mount_main                                          1152    1154      +2
findfs_main                                          125      80     -45
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(add/remove: 0/0 grow/shrink: 3/1 up/down: 42/-45)             Total: -3 bytes

Signed-off-by: Natanael Copa <natanael.copa@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/util-linux/Config.in b/util-linux/Config.in
index 5f5adc0..7cf1757 100644
--- a/util-linux/Config.in
+++ b/util-linux/Config.in
@@ -689,6 +689,7 @@
 	help
 	  This allows for specifying a device by label or uuid, rather than by
 	  name. This feature utilizes the same functionality as blkid/findfs.
+	  This also enables label or uuid support for swapon.
 
 config FEATURE_MOUNT_NFS
 	bool "Support mounting NFS file systems"