Fix spelling

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Haakan T Johansson <f96hajo@chalmers.se>
Closes #5547 
Closes #5543

lib/libshare/nfs.c

@@ -723,7 +723,7 @@ nfs_check_exportfs(void)
 }
 
 /*
- * Provides a convenient wrapper for determing nfs availability
+ * Provides a convenient wrapper for determining nfs availability
  */
 static boolean_t
 nfs_available(void)

lib/libspl/include/atomic.h

@@ -247,7 +247,7 @@ extern uint64_t atomic_swap_64(volatile uint64_t *, uint64_t);
 
 /*
  * Perform an exclusive atomic bit set/clear on a target.
- * Returns 0 if bit was sucessfully set/cleared, or -1
+ * Returns 0 if bit was successfully set/cleared, or -1
  * if the bit was already set/cleared.
  */
 extern int atomic_set_long_excl(volatile ulong_t *, uint_t);

lib/libspl/include/sys/dkio.h

@@ -158,7 +158,7 @@ struct dk_geom {
 
 /*
  * The following ioctls are generic in nature and need to be
- * suported as appropriate by all disk drivers
+ * supported as appropriate by all disk drivers
  */
 #define	DKIOCGGEOM	(DKIOC|1)		/* Get geometry */
 #define	DKIOCINFO	(DKIOC|3)		/* Get info */

lib/libspl/include/sys/dklabel.h

@@ -107,7 +107,7 @@ struct dk_map2 {
 
 struct dkl_partition    {
 	uint16_t	p_tag;		/* ID tag of partition */
-	uint16_t	p_flag;		/* permision flags */
+	uint16_t	p_flag;		/* permission flags */
 	daddr32_t	p_start;	/* start sector no of partition */
 	int32_t		p_size;		/* # of blocks in partition */
 };

lib/libzfs/libzfs_pool.c

@@ -902,7 +902,7 @@ zpool_prop_get_feature(zpool_handle_t *zhp, const char *propname, char *buf,
 
 	/*
 	 * Convert from feature name to feature guid. This conversion is
-	 * unecessary for unsupported@... properties because they already
+	 * unnecessary for unsupported@... properties because they already
 	 * use guids.
 	 */
 	if (supported) {