Use more portable switch for uniq to unbreak osx build

tests/test-duplicate-symbols.sh

@@ -5,7 +5,7 @@ EXPORTS=`find "${SOURCE_PATH}" -name "*exports"`
 
 ERRORS=0
 for E in $EXPORTS; do
-	NUM_DUPES=`sort $E | uniq -D | wc -l`
+	NUM_DUPES=`sort $E | uniq -d | wc -l`
 	if [[ "$NUM_DUPES" != 0 ]]; then
 		echo "There are duplicate symbols in '$E'"
 		ERRORS=1