Make check-libcxx dependant on libc++experimental if present.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@268451 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 34a559d..ae6fee1 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -44,10 +44,14 @@
   ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
   @ONLY)
 
+if (LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY)
+  set(experimental_dep cxx_experimental)
+endif()
+
 add_lit_testsuite(check-libcxx
   "Running libcxx tests"
   ${CMAKE_CURRENT_BINARY_DIR}
-  DEPENDS cxx)
+  DEPENDS cxx ${experimental_dep})
 
 if (LIBCXX_GENERATE_COVERAGE)
   include(CodeCoverage)