Android: Add information about LLVM libc++ license

When building with the android-clang mkspec, we will use the
MIT-licensed run-time instead of the GPL-licensed one. This was
not reflected in the documentation.

Change-Id: Icb081218fbc5a1ac63a422dfb06e28ff077204d9
Reviewed-by: BogDan Vatra <bogdan@kdab.com>

doc/src/legal/android-runtime-licensing-notes.qdoc

@@ -35,17 +35,19 @@ The Android platform does not provide a full implementation of the C++ run-time.
 apps that depend on features such as STL, exceptions, or RTTI, must include an additional
 native run-time library that provides the features they need.
 
-Qt will by default use the GNU libstdc++ library which is distributed as part of the Google Android NDK.
-Qt Creator will copy this library into the .APK for any Qt-based Android app. The library will then be
-loaded by the app on start-up to meet the run-time requirements of Qt.
-
-The GNU C++ run-time is licensed under the
+When built with g++, Qt will use the GNU libstdc++ library which is distributed as part of the Google
+Android NDK. Qt Creator will copy this library into the .APK for any Qt-based Android app. The library
+will then be loaded by the app on start-up to meet the run-time requirements of Qt.The GNU C++ run-time
+is licensed under the
 \l{http://gcc.gnu.org/onlinedocs/libstdc++/manual/appendix_gpl.html}{GNU General Public License version 3} with
 an exception which grants permission for run-time linking and usage of the library by an application which
 would otherwise violate the terms of the main license. For more information about this exception, see
 \l{http://gcc.gnu.org/onlinedocs/libstdc++/manual/license.html}{the official license page}.
 
-\section1 Information About License From GCC Headers
+When Qt is built with clang instead, it will use LLVM's libc++, which is dual-licensed under both the
+University of Illinois "BSD-Like" license and the MIT license.
+
+\section1 Information About The GNU C++ Run-time License From GCC Headers
 
 This file is part of the GNU ISO C++ Library.  This library is free
 software; you can redistribute it and/or modify it under the terms
@@ -142,6 +144,84 @@ The availability of this Exception does not imply any general
 presumption that third-party software is unaffected by the copyleft
 requirements of the license of GCC.
 
+\section1 Information About The LLVM C++ Run-time License
+
+==============================================================================
+libc++ License
+==============================================================================
+
+The libc++ library is dual licensed under both the University of Illinois
+"BSD-Like" license and the MIT license.  As a user of this code you may choose
+to use it under either license.  As a contributor, you agree to allow your code
+to be used under both.
+
+Full text of the relevant licenses is included below.
+
+==============================================================================
+
+University of Illinois/NCSA
+Open Source License
+
+Copyright (c) 2009-2017 by the contributors listed in CREDITS.TXT
+
+All rights reserved.
+
+Developed by:
+
+    LLVM Team
+
+    University of Illinois at Urbana-Champaign
+
+    http://llvm.org
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal with
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+    * Redistributions of source code must retain the above copyright notice,
+      this list of conditions and the following disclaimers.
+
+    * Redistributions in binary form must reproduce the above copyright notice,
+      this list of conditions and the following disclaimers in the
+      documentation and/or other materials provided with the distribution.
+
+    * Neither the names of the LLVM Team, University of Illinois at
+      Urbana-Champaign, nor the names of its contributors may be used to
+      endorse or promote products derived from this Software without specific
+      prior written permission.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
+SOFTWARE.
+
+==============================================================================
+
+Copyright (c) 2009-2014 by the contributors listed in CREDITS.TXT
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
 
 */