This plugin causes the application applic.c to invoke DMTCP
to checkpoint itself.  In this example, the plugin could be omitted.

Note the need to compile with -fPIC the target file that uses dmtcpCheckpoint().
This is needed so that the same binary can used both with and without DMTCP.

This example is sufficient for most application, but more advanced
hooks to DMTCP are also listed in applic.c .
