Use this function to create the install targets rather than doing so
manually, which gains us the `-stripped` install targets to perform
stripped installations.

Differential Revision: https://reviews.llvm.org/D40675

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@319489 91177308-0d34-0410-b5e6-96231b3b80d8