[llvm] Update module map to include the `IR/ConstantFold` header

This should fix the build failure occuring when enabling modules
(LLVM_ENABLE_MODULES=On):

https://green.lab.llvm.org/green/job/lldb-cmake/44785/

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>

llvm/include/llvm/module.modulemap

@@ -244,6 +244,7 @@ module LLVM_intrinsic_gen {
     export *
   }
   module IR_AbstractCallSite { header "IR/AbstractCallSite.h" export * }
+  module IR_ConstantFold { header "IR/ConstantFold.h" export * }
   module IR_ConstantFolder { header "IR/ConstantFolder.h" export * }
   module IR_GlobalVariable { header "IR/GlobalVariable.h" export * }
   module IR_NoFolder { header "IR/NoFolder.h" export * }