Workaround bugs in std::vector<bool> on msvc 7.1.

Thanks to Rob Lievaart for reporting/diagnosing this.


[SVN r23372]

libs/program_options

@@ -1 +1 @@
-Subproject commit 07f98fc711e43aabb364dba8365ea4946794ac38
+Subproject commit fec30e0c6cb73166b86226b0ca581a518a25cb8c