don't use 'localversion*' files twice

Since we look in both source and object directories for localversion*
files, we accidentally ended up getting them twice.  Use 'sort -u' to
avoid that.
Reported-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Makefile

@@ -789,7 +789,7 @@ $(vmlinux-dirs): prepare scripts
 
 pattern = ".*/localversion[^~]*"
 string  = $(shell cat /dev/null \
-	   `find $(objtree) $(srctree) -maxdepth 1 -regex $(pattern) | sort`)
+	   `find $(objtree) $(srctree) -maxdepth 1 -regex $(pattern) | sort -u`)
 
 localver = $(subst $(space),, $(string) \
 			      $(patsubst "%",%,$(CONFIG_LOCALVERSION)))