Instead of expecting callers to set this member accodingly so that later
at dso destruction it can, if needed, be correctly free()d, make it a
requirement by passing it as a parameter to dso__set_long_name.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-na7t1tqim22vuqkt4zq5n4ri@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>