use (0) to represent zero rather then default constructor.

(1) is require anyway so this does not add further requirements


[SVN r24763]

libs/numeric/ublas

@@ -1 +1 @@
-Subproject commit 63788a6dd2a459181e69622bcc19d4dcee617bcc
+Subproject commit ec38ea22e6b3a850a7b95a1f10329829cfc4962a