fixes issue 865 + allow 0 for PORT_MESSAGE DataLength
fixes issue 865
+ allow 0 for PORT_MESSAGE DataLength

SVN-Revision: 825

LohithBlaze/drmemory,LohithBlaze/drmemory,sigma-random/drmemory,LohithBlaze/drmemory,code4bones/drmemory,sigma-random/drmemory,code4bones/drmemory,LohithBlaze/drmemory,code4bones/drmemory,code4bones/drmemory,sigma-random/drmemory,LohithBlaze/drmemory,sigma-random/drmemory,code4bones/drmemory,sigma-random/drmemory