pmdaproc: several fixes for test qa/370 (sar2pcp)
pmdaproc: several fixes for test qa/370 (sar2pcp)

Resolves several problems Lukas, Miloš and I have encountered
in this test in the last couple of days -
- loosen fuzzy matching for floating-point imprecision a bit;
- handle an AM/PM failure Lukas observed on a buildbot, where
  bit-after-midnight values were reported as bit-after-noon.
- the sar input data is currently all x86_64-specific, and so
  this test fails on other platforms like s390x, ppc, etc; in
  the short-term use _notrun to avoid this issue.  Over time,
  we need to add archives with arch-specific sar2pcp input.

wuliming/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,wuliming/pcp,wuliming/pcp,wuliming/pcp,adfernandes/pcp,wuliming/pcp,wuliming/pcp,wuliming/pcp,wuliming/pcp,adfernandes/pcp,adfernandes/pcp