[runtimes] Move the enable_rtti Lit parameter to the DSL

GitOrigin-RevId: ff0d4367bf0b219fb69612f856892701eb2b1a8c
diff --git a/test/libcxxabi/test/config.py b/test/libcxxabi/test/config.py
index b9b2b6e..45fb0f5 100644
--- a/test/libcxxabi/test/config.py
+++ b/test/libcxxabi/test/config.py
@@ -83,6 +83,3 @@
                 self.lit_config.fatal("libunwind_headers='%s' is not a directory."
                                       % libunwind_headers)
             self.cxx.compile_flags += ['-I' + libunwind_headers]
-
-    def configure_compile_flags_rtti(self):
-        pass