SPECS/bcc.spec: add dependencies to libdebuginfod

SPECS/bcc.spec: add dependencies to libdebuginfod

On Fedora builds we can check the version number and add
build and runtime dependencies to debuginfod for all
currently supported releases (>= 32). Note that the buildbot
only has Fedora 25-28 so it will not try to build libbcc
with debuginfod support as the required packages are not
available on these releases.

For .deb packages there is no easy way to add dependencies
dynamically, so we do not add dependencies to libdebuginfod
there for now. For documentation purposes, however, let's
add a comment indicating which changes are required for
libdebuginfod support for downstream maintainers.

Signed-off-by: Andreas Ziegler <andreas.ziegler@fau.de>