hdf5_ep

[svn-r14458] Fixed coredump under production 64-bit solaris.

As best I can tell, H5C_make_space_in_cache() was accessing memory 
that had been deallocated -- however the bug was easy to mask, and 
jumped around even in different runs of the same executable.  While 
I was never able to generate a definitive test case that exposed 
exactly where the core dump occured, I was able to generate print 
statement traces which made it clear that I was accessing freed
memory.

In any case, reworking the code to avoid the reference to freed
cache entries seems to have fixed the problem.

Tested serial production on Phoenix, and commit tested.  Also, 
partial tests Linew.