h2o{,-devel}: Improve rc.d/h2o, freshen h2o.conf

rc.d/h2o:

• Add a configtest target
• Fix a bug that could prevent the script from locating the PIDfile path

h2o.conf:

• Remove entries that are defaults

PR: 238888
Approved by: maintainer (dch)
MFH: 2019Q2