perf report: Don't abbreviate file paths relative to the cwd

This avoids around some problems where the full path is executables and DSOs it
needed for finding debug symbols on platforms with separated debug symbol files
such as Ubuntu.  This is simpler than tracking an extra name for each image.

The only impact should be that paths in verbose output from the perf tools
become absolute, instead of relative to .

LKML-Reference: <new-submission>
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>