[CMake] Fix handling of passing through semi-colon separated lists.

When passing around CMake arguments as lists of arguments any arguments containing lists need to have their semi-colons escaped otherwise CMake will split the arguments in the middle.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253719 91177308-0d34-0410-b5e6-96231b3b80d8

cmake/modules/LLVMExternalProjectUtils.cmake

@@ -93,8 +93,9 @@ function(llvm_ExternalProject_Add name source_dir)
   get_cmake_property(variableNames VARIABLES)
   foreach(varaibleName ${variableNames})
     if(varaibleName MATCHES "^${nameCanon}")
+      string(REPLACE ";" "\;" value "${${varaibleName}}")
       list(APPEND PASSTHROUGH_VARIABLES
-        -D${varaibleName}=${${varaibleName}})
+        -D${varaibleName}=${${value}})
     endif()
   endforeach()