[CMake] llvm-diff depends on intrinsics_gen

[CMake] llvm-diff depends on intrinsics_gen

llvm-diff.cpp has the following include chain:

llvm/IR/Module.h
llvm/IR/Function.h
llvm/IR/Argument.h
llvm/IR/Attributes.h
llvm/IR/Attributes.gen

This means llvm-diff needs to depend on intrinsics_gen.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287427 91177308-0d34-0410-b5e6-96231b3b80d8