private static void usage(String[] args) {
		for (int i = 0; i < args.length; i++) {
			System.err.println("arg " + i + ": " + args[i]);
		}
		String invocationName = System.getProperty(INVOCATION_NAME_PROPERTY);

		StringBuffer buf = new StringBuffer();
		buf.append("\nUsage: ");
		buf.append(invocationName != null ? invocationName : "GhidraJarBuilder");
		buf.append(
			" [-output <output file>] [-srczip <src zip output file>] [-bin <compiled classes dir>] [-main <main-class>]\n");
		System.err.println(buf.toString());
		System.exit(0);
	}
Puts a directory in the jar for Ghidra Extensions. This may be empty (if
no extensions are installed) but should exist nonetheless.

@throws IOException if there's an error writing to the jar
Ghidra/Features/Base/src/main/java/ghidra/util/GhidraJarBuilder.java