This commit adds a help message when system limitations prevent setting up OSHMEM's symmetric heap. This fixes #4399 and should be added to  

cmr=v1.7.5:reviewer=jsquyres
Follow on to r31172: improve the help message

* Show the help message for all errors, not just EINVAL
* Put the help message in the correct helpfile
* Fix grammar and spelling, and expand the help message

cmr=v1.7.5:ticket=#4431