[lldb][test] Fix TestStdCXXDisassembly test

The path llvm#98694 was not enough. This test is still failed on the buildbot https://lab.llvm.org/staging/#/builders/195/builds/4438
Use `USE_LIBSTDCPP := 1` instead.

Author: slydiman

lldb/test/API/lang/cpp/stl/Makefile

@@ -1,5 +1,5 @@
 CXX_SOURCES := main.cpp
 
-USE_SYSTEM_STDLIB := 1
+USE_LIBSTDCPP := 1
 
 include Makefile.rules