build: rename " and "" to quote1 and quote2 for hg

They'll be copied back during installation
but then hg doesn't have to create those files
on systems that have trouble with them.

TBR=rsc
https://codereview.appspot.com/105800043

INSTALL

@@ -170,6 +170,10 @@ if $dobuild; then
 		echo " "
 		echo "* Warning: not all binaries built successfully."
 	fi
+	if [ -f bin/quote1 ]; then
+		cp bin/quote1 'bin/"'
+		cp bin/quote2 'bin/""'
+	fi
 	echo "* Cleaning up..."
 	mk clean
 fi