Add static assertion on selfadjoint-view's UpLo parameter.

(grafted from d820ab9edc
)

Eigen/src/Core/util/StaticAssert.h

@@ -101,7 +101,8 @@
         THIS_TYPE_IS_NOT_SUPPORTED=1,
         STORAGE_KIND_MUST_MATCH=1,
         STORAGE_INDEX_MUST_MATCH=1,
-        CHOLMOD_SUPPORTS_DOUBLE_PRECISION_ONLY=1
+        CHOLMOD_SUPPORTS_DOUBLE_PRECISION_ONLY=1,
+        SELFADJOINTVIEW_ACCEPTS_UPPER_AND_LOWER_MODE_ONLY=1
       };
     };