edk2: Change License.txt from 2-Clause BSD to BSD+Patent

Change License.txt in the root of the edk2 repository from the
2-Clause BSD License to the BSD+Patent License.

The text difference between these licenses in the patch is larger
than expected due to different choices for the position of the line
breaks.  The text from the BSD 2-Clause license and its disclaimer
are the same.  New clauses from the BSD+Patent license have been
added.

https://bugzilla.tianocore.org/show_bug.cgi?id=1373

This change is based on the following emails:

  https://lists.01.org/pipermail/edk2-devel/2019-February/036260.html
  https://lists.01.org/pipermail/edk2-devel/2018-October/030385.html

RFCs with detailed process for the license change:

  V3: https://lists.01.org/pipermail/edk2-devel/2019-March/038116.html
  V2: https://lists.01.org/pipermail/edk2-devel/2019-March/037669.html
  V1: https://lists.01.org/pipermail/edk2-devel/2019-March/037500.html

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

License.txt

@@ -1,29 +1,51 @@
-Copyright (c) 2004 - 2016, Intel Corporation. All rights reserved.
-Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.
-Copyright (c) 2011 - 2015, ARM Limited. All rights reserved.
-Copyright (c) 2014 - 2015, Linaro Limited. All rights reserved.
-Copyright (c) 2013 - 2015, Red Hat, Inc.
+Copyright (c) 2019, TianoCore and contributors.  All rights reserved.
+
+SPDX-License-Identifier: BSD-2-Clause-Patent
 
 Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions
-are met:
+modification, are permitted provided that the following conditions are met:
 
-* Redistributions of source code must retain the above copyright
-  notice, this list of conditions and the following disclaimer.
-* Redistributions in binary form must reproduce the above copyright
-  notice, this list of conditions and the following disclaimer in
-  the documentation and/or other materials provided with the
-  distribution.
+1. Redistributions of source code must retain the above copyright notice,
+   this list of conditions and the following disclaimer.
 
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
-FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
-COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
-INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
-BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
-CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
-LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
-ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+Subject to the terms and conditions of this license, each copyright holder
+and contributor hereby grants to those receiving rights under this license
+a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+(except for failure to satisfy the conditions of this license) patent
+license to make, have made, use, offer to sell, sell, import, and otherwise
+transfer this software, where such license applies only to those patent
+claims, already acquired or hereafter acquired, licensable by such copyright
+holder or contributor that are necessarily infringed by:
+
+(a) their Contribution(s) (the licensed copyrights of copyright holders and
+    non-copyrightable additions of contributors, in source or binary form)
+    alone; or
+
+(b) combination of their Contribution(s) with the work of authorship to
+    which such Contribution(s) was added by such copyright holder or
+    contributor, if, at the time the Contribution is added, such addition
+    causes such combination to be necessarily infringed. The patent license
+    shall not apply to any other combinations which include the
+    Contribution.
+
+Except as expressly stated above, no rights or licenses from any copyright
+holder or contributor is granted under this license, whether expressly, by
+implication, estoppel or otherwise.
+
+DISCLAIMER
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 POSSIBILITY OF SUCH DAMAGE.