Fix build with newer versions of CMake.

Obtained with some adaptions from:

https://github.com/keystone-engine/keystone/pull/593

--- src/CMakeLists.txt.orig	2020-06-21 14:08:17 UTC
+++ src/CMakeLists.txt
@@ -1,7 +1,7 @@
 # Keystone Assembler Engine (www.keystone-engine.org)
 # By Nguyen Anh Quynh, 2016
 
-cmake_minimum_required(VERSION 2.8.7)
+cmake_minimum_required(VERSION 3.10.0)
 project(keystone)
 
 set(KEYSTONE_VERSION_MAJOR 0)
@@ -12,23 +12,6 @@ if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_T
 if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
   message(STATUS "No build type selected, default to Debug")
   set(CMAKE_BUILD_TYPE "Debug")
-endif()
-
-if (POLICY CMP0022)
-  cmake_policy(SET CMP0022 NEW) # automatic when 2.8.12 is required
-endif()
-
-if (POLICY CMP0051)
-  # CMake 3.1 and higher include generator expressions of the form
-  # $<TARGETLIB:obj> in the SOURCES property.  These need to be
-  # stripped everywhere that access the SOURCES property, so we just
-  # defer to the OLD behavior of not including generator expressions
-  # in the output for now.
-  cmake_policy(SET CMP0051 OLD)
-endif()
-
-if (POLICY CMP0063)
-  set(CMAKE_POLICY_DEFAULT_CMP0063 NEW) # automatic when 3.3.2 is required
 endif()
 
 if (CMAKE_VERSION VERSION_LESS 3.1.20141117)
--- src/llvm/CMakeLists.txt.orig	2020-06-21 14:08:05 UTC
+++ src/llvm/CMakeLists.txt
@@ -1,25 +1,12 @@
 # See docs/CMake.html for instructions about how to build LLVM with CMake.
 
-cmake_minimum_required(VERSION 2.8.7)
+cmake_minimum_required(VERSION 3.10.0)
 
 set(LLVM_INSTALL_TOOLCHAIN_ONLY ON)
 
 if (NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
   message(STATUS "No build type selected, default to Debug")
   set(CMAKE_BUILD_TYPE "Debug")
-endif()
-
-if(POLICY CMP0022)
-  cmake_policy(SET CMP0022 NEW) # automatic when 2.8.12 is required
-endif()
-
-if (POLICY CMP0051)
-  # CMake 3.1 and higher include generator expressions of the form
-  # $<TARGETLIB:obj> in the SOURCES property.  These need to be
-  # stripped everywhere that access the SOURCES property, so we just
-  # defer to the OLD behavior of not including generator expressions
-  # in the output for now.
-  cmake_policy(SET CMP0051 OLD)
 endif()
 
 if(CMAKE_VERSION VERSION_LESS 3.1.20141117)
