[pcp] pcp updates - more derived metrics

[Ken McDonell]

Took gcov for a spin, even patched Greg's ggcov to make it work, sort
of, with the not-so-Karmic Koala ... no real problems, but some dead
code that can be poxed off.

Changes committed to git://oss.sgi.com/kenj/pcp.git dev

 src/libpcp/src/derive.c       |   54 +++----
 src/libpcp/src/derive.h       |   26 +--
 src/libpcp/src/derive_fetch.c |  306 ++++++++++++++----------------------------
 src/pmdas/sample/help         |    6 
 src/pmdas/sample/pmns         |   11 +
 src/pmdas/sample/src/sample.c |   25 +++
 6 files changed, 181 insertions(+), 247 deletions(-)

commit 44e7728d3b34ad185c4a924711e6d994b1e0966e
Author: Ken McDonell <kenj at internode.on.net>
Date:   Mon Jan 4 08:06:34 2010 +1100

    Derived metrics - refinement
    
    After gcov analysis and some expanded coverage in the QA suite, there
    is some dead code removal here, and additional metrics in the sample
    PMDA.