[clang] Add llvm-strip to test dependencies

CodeGen/thinlto_embed_bitcode.ll relies on it.
diff --git a/clang/test/CMakeLists.txt b/clang/test/CMakeLists.txt
index a913b35..562a148 100644
--- a/clang/test/CMakeLists.txt
+++ b/clang/test/CMakeLists.txt
@@ -122,6 +122,7 @@
     llvm-profdata
     llvm-readelf
     llvm-readobj
+    llvm-strip
     llvm-symbolizer
     opt
     split-file