When configuring a system-wide couting PMC, hwpmc was incorrectly logging
process mappings for that PMC. Nothing ever reads pmc logs out of a
counting PMC, so the log buffers were leaked when the PMC was
deconfigured. The process mappings are only useful for sampling PMCs
anyway, so only log the mappings if the PMC is a sampling PMC.
This bug would cause allocating sample-mode PMCs to fail with ENOMEM
after allocating several counting-mode PMCs.
Approved by: emaste (mentor)