[cmake] Set variables before saving them

[smeenai]

Summary

Otherwise init_user_prop will just save empty values for these
variables, which will break sub-configures.

[smeenai]

D121035 makes this unnecessary.

llvm/cmake/platforms/WinMsvc.cmake

foreach(entry ${entries})
     endif()
   endforeach()
 endfunction()
 
 set(CMAKE_SYSTEM_NAME Windows)
 set(CMAKE_SYSTEM_VERSION 10.0)
 set(CMAKE_SYSTEM_PROCESSOR AMD64)
 
+if (NOT MSVC_VER)
+  get_highest_version("${LLVM_WINSYSROOT}/VC/Tools/MSVC" MSVC_VER)
+endif()
+
+if (NOT WINSDK_VER)
+  get_highest_version("${LLVM_WINSYSROOT}/Windows Kits/10/Include" WINSDK_VER)
+endif()
+
 init_user_prop(HOST_ARCH)
 init_user_prop(LLVM_NATIVE_TOOLCHAIN)
 init_user_prop(LLVM_WINSYSROOT)
 init_user_prop(MSVC_VER)
 init_user_prop(WINSDK_VER)
 
 if(NOT HOST_ARCH)
   set(HOST_ARCH x86_64)

 if(NOT EXISTS "${LLVM_NATIVE_TOOLCHAIN}/bin/clang-cl" OR
    NOT EXISTS "${LLVM_NATIVE_TOOLCHAIN}/bin/lld-link")
   message(SEND_ERROR
           "LLVM_NATIVE_TOOLCHAIN folder '${LLVM_NATIVE_TOOLCHAIN}' does not "
           "point to a valid directory containing bin/clang-cl and bin/lld-link "
           "binaries")
 endif()
 
-if (NOT MSVC_VER)
-  get_highest_version("${LLVM_WINSYSROOT}/VC/Tools/MSVC" MSVC_VER)
-endif()
-
-if (NOT WINSDK_VER)
-  get_highest_version("${LLVM_WINSYSROOT}/Windows Kits/10/Include" WINSDK_VER)
-endif()
-
 if (NOT LLVM_WINSYSROOT OR NOT MSVC_VER OR NOT WINSDK_VER)
   message(SEND_ERROR
           "Must specify CMake variable LLVM_WINSYSROOT, MSVC_VER and WINSDK_VER")
 endif()
 
 set(ATLMFC_LIB     "${LLVM_WINSYSROOT}/VC/Tools/MSVC/${MSVC_VER}/atlmfc/lib")
 set(MSVC_INCLUDE   "${LLVM_WINSYSROOT}/VC/Tools/MSVC/${MSVC_VER}/include")
 set(MSVC_LIB       "${LLVM_WINSYSROOT}/VC/Tools/MSVC/${MSVC_VER}/lib")