[clang] Only call find_package(Z3) if CLANG_ANALYZER_BUILD_Z3 is ON
[clang] Only call find_package(Z3) if CLANG_ANALYZER_BUILD_Z3 is ON

Backport of upstream commit.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@311858 91177308-0d34-0410-b5e6-96231b3b80d8

olifre/root,karies/root,karies/root,root-mirror/root,olifre/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,karies/root,olifre/root,karies/root,root-mirror/root,karies/root,olifre/root,karies/root,karies/root,root-mirror/root,root-mirror/root,olifre/root,olifre/root,olifre/root,root-mirror/root,olifre/root,olifre/root,karies/root,root-mirror/root,karies/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,karies/root