[petsc-users] change lib names

[Sam Guo]

Dear PETSc team,
  I like to change petsc lib name to petsc_real or petsc_complex to
distinguish real vs complex version. Simply copy of libpetsc to
libpetsc_real does not help. I need to update PETSc makefile to recompile
but I have troubles to figure out where PETSc makefile decides the lib
name.

Thanks,
Sam