build: enable CMake policy 0077

Enable CMake policy 77. This alters the behavior of option. The old behavior
would remove the value of the option from the cache and create a new one. The
new behavior does not create the variable if it is defined already. This ensures
that subsequent reconfigures will behave identically. This seems better than the
setting of OLD - the desire is to ensure that it is set to OLD or NEW.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@361307 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0164d3eaa8fac0844698f9b6cb802f90f15ded14..0f8ddd87e02cc549f3a6f2f2b395423abdf76bb7 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,6 +11,10 @@ if(POLICY CMP0075)
   cmake_policy(SET CMP0075 NEW)
 endif()
 
+if(POLICY CMP0077)
+  cmake_policy(SET CMP0077 NEW)
+endif()
+
 if(NOT DEFINED LLVM_VERSION_MAJOR)
   set(LLVM_VERSION_MAJOR 9)
 endif()