CMake: Only include LLVM example executables in the build if requested by the user

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73566 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index de3e159..543ee7f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -287,7 +287,10 @@
 add_subdirectory(projects)
 add_subdirectory(tools)
 
-add_subdirectory(examples)
+option(LLVM_EXAMPLES "Build LLVM example programs." OFF)
+if (LLVM_EXAMPLES)
+  add_subdirectory(examples)
+endif ()
 
 install(DIRECTORY include
   DESTINATION .