pcp

PM_TYPE_EVENT support - round one

Initial changes to support PM_TYPE_EVENT and the pmEventParameter,
pmEventRecord and pmEventArray structures.

Note no endian conversions for PDUs and no pmUnpackEventRecords()
routine as yet.

Also added PM_ERR_TYPE to catch cases in which not all types are
supported for some operations and new macros to help size objects
to a PDU unit boundary (PM_PDU_SIZE and PM_PDU_SIZE_BYTES).

Refined pmdaFetchCallBack semantics for PMDA_INTERFACE_5 to allow
additional return value to indicate strings and aggregates can
be freed after __pmStuffValue has been called - new macros to
make intent more obvious, PMDA_FETCH_NOVALUES, PMDA_FETCH_STATIC
and PMDA_FETCH_DYNAMIC (for the new case).

And sample.event.* metrics are new for the sample PMDA.

Changes in these places: pmapi.h, pmExtractValue(), pmErrStr(),
__pmStuffValue(), pmAtomStr(), pmPrintValue(), __pmPrintDesc(),
sample PMDA.