verify_sdp.sh v5.20.0:
* New checks: /p4/N/bin/p4{d,p,broker}_N need correct symlink target,
and must exist if the corresponding _init script exists.
For p4d, it can be a symlink (for a case-sensitive instance) or script
(for a case-insensitive instance to pass the C1 flag). Either way the
target is checked.
These checks cannot be skipped or converted to warnings.
* Added check that /p4/N/bin/p4{d,p,broker}_N_init scripts have content
that matches templates. This can be skipped with '-skip' or reported as
mere warnings (with '-warn') with a new and documented 'init' category
of test skipping/warning.