DMTCP 2.3 released

This is primarily a bug fix release. However, if you are using DMTCP
for the ARM v7 CPU, or if you are using DMTCP either with the InfiniBand
network or with the SLURM batch system, then it is strongly recommended
to upgrade.

The primary changes for this release are:

• Bug fix affecting building for ARM on some recent armv7a CPUs.
• Improvements in support for InfiniBand network and for SLURM
  batch system.
• Other smaller bug fixes.