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

Change contents of License.txt in OvmfPkg of the edk2 repository
from the 2-Clause BSD License to the BSD+Patent License for the
default license type.  Preserve the contents related to the use
of the MIT license in this file.

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>

OvmfPkg/License.txt

@@ -1,29 +1,56 @@
-Copyright (c) 2012, Intel Corporation. All rights reserved.
+Copyright (c) 2012 - 2019, Intel Corporation. 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:
-
-* 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.
-
-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
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice,
+   this list of conditions and the following disclaimer.
+
+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.
 
+================================================================================
 
 Some files are subject to the following license, the MIT license. Those files
 are located in: