Add platform/external/libcxxrt

default.xml

@@ -158,6 +158,7 @@
   <project path="external/libcap-ng" name="platform/external/libcap-ng" />
   <project path="external/libcxx" name="platform/external/libcxx" />
   <project path="external/libcxxabi" name="platform/external/libcxxabi" />
+  <project path="external/libcxxrt" name="platform/external/libcxxrt" />
   <project path="external/libffi" name="platform/external/libffi" />
   <project path="external/libgsm" name="platform/external/libgsm" groups="pdk" />
   <project path="external/liblzf" name="platform/external/liblzf" groups="pdk" />