This removes `-lpytrilinos` from Makefile.export.Trilinos so that C code
trying to link against a Trilinos built with PyTrilinos does not fail
due to undefined references to python routines (libpytrilinos is only
used when importing PyTrilinos in python, in which case those references
are already defined by Python).
There was already a bit of code to do something similar for C codes
importing Trilinos via a CMake mechanism, this extends that to a basic
Makefile mechanism as well. This patch also updates the comments to
remove a stale link discussing this issue, and replacing with links to
the some Trilinos issue reports related to the matter.
eee4522103