Fake ELF sonames by default (again)

Fake ELF sonames by default (again)

- (Private) libraries which might intentionally not have DT_SONAME
  are still recorded as requires from DT_NEEDED, and there's no
  way of knowing what's an internal library when generating requires.
  Not faking the soname in these cases will only result in broken
  requires in cases that always used to "just work".
- Change the switch to --no-fake-soname disabler instead to allow
  tweaking in special cases but by default we gotta match linker
  (and ELF specification) behavior, no matter how much we'd like to
  use this for our own heuristics :-/
(cherry picked from commit b6f159a34c946b75cb95a7862968ff4e8eb74fe6)