gh-1262: Allow to disable backtraces entirely

* Fix hardening if backtraces are off
* Ensure that all tests are passed with hardened flags
* RPM: add --with/--without backtrace option (default is --with)
* RPM: remove dependency on libbfd, libiberty, libz if --without backtrace
* RPM: enable stripping and debuginfo if --without backtrace

Backtraces are still enabled by default.

Hardened flags used by RedHat:

  -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2
  -fstack-protector-strong --param=ssp-buffer-size=4
  -pie -fPIC