Improve AM_SILENT_RULES coverage

Improve AM_SILENT_RULES coverage

Note, elfutils does not explicitly enable AM_SILENT_RULES.  It's only
available starting from automake 1.11, but starting from automake 1.13
silent rules are always generated, defaulting to verbose.  $(AM_V_foo)
additions should be no-ops on systems that don't support silent rules.

To be silent, use "./configure --enable-silent-rules" or "make V=0".

Signed-off-by: Josh Stone <jistone@redhat.com>