Do not install lit-cpuid

Summary:
AFAIK, lit-cpuid is used by the tests. 
Installing it causes LLVMExports*.cmake files to depend
on this program.
It causes some serious packaging issues as it would means
that llvm-dev depends on lldb.

See:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=941082
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=941306

See also https://bugs.llvm.org/show_bug.cgi?id=43035
for a similar issue caused by
https://reviews.llvm.org/D56606

Reviewers: mgorny

Reviewed By: mgorny

Subscribers: delcypher, lldb-commits

Differential Revision: https://reviews.llvm.org/D68537

llvm-svn: 373819