BUG: Update both RPATH and RUNPATH entries

During installation the RPATH and RUNPATH entries of ELF binaries are
edited to match the user specification.  Usually either one entry is
present or both entries refer to the same string literal.  In the case
that they are both present and refer to separate string literals we need
to update both.  I have never seen this case in practice, but we should
do this just in case.