build-release.sh: make checksum process safer

Using "*" can make checksum process fails if any file in "dist"
directory starts with "-". With the form "./*", we eliminate this
problem without paying any more cost.

build-release.sh

@@ -69,7 +69,7 @@ checksum() {
 	fi
 
 	rm -f "dist/$CHECKSUM_FILE"
-	( cd dist && for x in *; do "${CHECKSUM_CMD[@]}" "$x" >> "$CHECKSUM_FILE"; done )
+	( cd dist && for x in ./*; do "${CHECKSUM_CMD[@]}" "$x" >> "$CHECKSUM_FILE"; done )
 }
 
 echo "--- Building Release: ${VERSION}"