bug-fix: power estimates

PowerTOP didn’t have a way to inform the user how many runs were needed
to show power estimates when testing battery power. This patch fixes
that problem.  PowerTOP uses a fitness function to approximate the power
estimates, hence the need to have many runs.  The more runs the more
precise the measurements.  For extra precise power measurements use
RAPLE and Power Cap support on Linux kernel.  These features were
released on Linux 3.13.  Latest kernel distributions have RAPLE and
Power Cap enabled.

Signed-off-by: Alexandra Yates <alexandra.yates@linux.intel.com>
Addition of two include guards

Unique include guards were added to two header files to make their reuse
a bit safer.
https://www.securecoding.cert.org/confluence/display/cplusplus/PRE06-CPP.+Enclose+header+files+in+an+inclusion+guard

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>