resulttool: Allow extraction of ptest data

resulttool: Allow extraction of ptest data

Rather than simply discarding the ptest data, change the code to discard
it when writing out the new testresult files, or optionally either preserve
it, or write it as seperate discrete logs.

This means the autobuilder should start writing out individual ptest log
files as well as allowing ueers to extract these manually.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>