Add eigen

Change-Id: Id586d1cc51100d526bcf06235282804b59ea1d5a
diff --git a/default.xml b/default.xml
index 072f9ae..2856862 100644
--- a/default.xml
+++ b/default.xml
@@ -75,6 +75,7 @@
   <project path="external/easymock" name="platform/external/easymock" />
   <project path="external/eclipse-basebuilder" name="platform/external/eclipse-basebuilder" />
   <project path="external/eclipse-windowbuilder" name="platform/external/eclipse-windowbuilder" />
+  <project path="external/eigen" name="platform/external/eigen" />
   <project path="external/elfutils" name="platform/external/elfutils" />
   <project path="external/embunit" name="platform/external/embunit" />
   <project path="external/emma" name="platform/external/emma" />