dmtcp_launch: Added --disable-all-plugins flag.

git-svn-id: svn://svn.code.sf.net/p/dmtcp/code/trunk@2583 ba6dc0ae-232f-0410-883f-9ebac64fc565
Change the MTCP_PROT_ZERO_PAGE value.

git-svn-id: svn://svn.code.sf.net/p/dmtcp/code/trunk@2584 ba6dc0ae-232f-0410-883f-9ebac64fc565