[petsc-dev] breaking all of PETSc to fix a design flaw

[Barry Smith]

   I am making a change to PETSc that will break everything. XXXDestroy(XXX) is replaced with XXXDestroy(XXX*) and in addition XXXDestroy(&x) returns immediately without error if x is null. 

   Won't be pushing until I've finished it all, it may take a few days.

   Barry