Add linux user disk support

This topic branch contains all the changes needed to integrate the user
side zfs tools with Linux style devices.  Primarily this includes fixing
up the Solaris libefi library to be Linux friendly, and integrating with
the libblkid library which is provided by e2fsprogs.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

lib/libefi/include/sys/uuid.h

@@ -74,12 +74,8 @@ struct uuid {
 	uint8_t		node_addr[6];
 };
 
-#define	UUID_LEN	16
-
 #define	UUID_PRINTABLE_STRING_LENGTH 37
 
-typedef uchar_t		uuid_t[UUID_LEN];
-
 /*
  * Convert a uuid to/from little-endian format
  */