update CHANGES for the 3.0.2 release
update version.m4 for 3.0.2 release

ABI string is bumped from c:r:a of 10:1:0 to 10:2:1.  Though changes
were made to mpi.h.in, none of them affect "interfaces" in the libtool
sense.  They merely affect some clang compile-time checking.

No reviewer.
update RELEASE_NOTES for the 3.0.2 release