RFR: JDK-8179879 Clarify install.sh

[Magnus Ihse Bursie]

Clarify the purpose of install.sh

Bug: https://bugs.openjdk.java.net/browse/JDK-8179879
Patch inline:
diff --git a/common/autoconf/build-aux/install.sh 
b/common/autoconf/build-aux/install.sh
--- a/common/autoconf/build-aux/install.sh
+++ b/common/autoconf/build-aux/install.sh
@@ -1,5 +1,28 @@
-#!/bin/sh
-echo >&2 "No suitable 'install' command found.'"
-echo >&2 "If automake is installed, running 'automake -fa'"
-echo >&2 "(and ignoring the errors) might produce one."
-exit 1
+#!/bin/bash
+#
+# Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+# DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+#
+# This code is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License version 2 only, as
+# published by the Free Software Foundation.  Oracle designates this
+# particular file as subject to the "Classpath" exception as provided
+# by Oracle in the LICENSE file that accompanied this code.
+#
+# This code is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+# version 2 for more details (a copy is included in the LICENSE file that
+# accompanied this code).
+#
+# You should have received a copy of the GNU General Public License version
+# 2 along with this work; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+# Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+# or visit www.oracle.com if you need additional information or have any
+# questions.
+#
+
+# This file is empty on purpose. It's a placeholder which is required by
+# autoconf, but it serves no purpose for us.

/Magnus