[Cmake] Add missing dependency for running tests.

This is needed now that we marked lldb-test as EXCLUDE_ALL, to
make sure `ninja lldb-test-deps` doesn't fail.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@358625 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4bf6168..a826c25 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -79,6 +79,9 @@
     list(APPEND LLDB_TEST_DEPS darwin-debug)
   endif()
 
+  # lldb-test is an hard dependency for the testsuite.
+  list(APPEND LLDB_TEST_DEPS lldb-test)
+
   if(TARGET lldb-server)
     list(APPEND LLDB_TEST_DEPS lldb-server)
   endif()