Clang needs dtor in the cc file (build fix)

BUG=none
TEST=one

TBR=shess
Review URL: http://codereview.chromium.org/7131008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@88145 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/base/version.h b/base/version.h
index 7dcefb3..e03b01a 100644
--- a/base/version.h
+++ b/base/version.h
@@ -21,6 +21,8 @@
   // Version object is assign to it.
   Version();
 
+  ~Version();
+
   // Initializes from a decimal dotted version number, like "0.1.1".
   // Each component is limited to a uint16. Call IsValid() to learn
   // the outcome.