corelens: Detect & load supported kernel module debuginfo files

[sobeckij]

When corelens runs, it detects modules but then just flags that it has no debuginfo.

It's required to manually extract the module debuginfo.

Workaround:
DRGN -x $vmcore to extract, and then you can re-run the corelens command.

Suggestion:

Extract the modules if they are detected as loaded in the vmcore, or otherwise skip the helper and do not display the 'failure' message.

Example:

$ tail corelens
Running module sys... completed in 0.211s
Running module irq... completed in 0.035s
Running module scsiinfo... completed in 0.001s
Running module virtio... completed in 0.005s
Running module virt... completed in 0.000s
Running module wq... completed in 0.204s
error: dm skipped because 'dm_mod' did not have debuginfo loaded
error: rds skipped because 'rds' did not have debuginfo loaded
error: multipath skipped because 'dm_mod' did not have debuginfo loaded

[brenns10]

Incidentally, this will be possible once #175 is merged. And in fact it will be default behavior on internal analysis systems. External systems would need to download debuginfo RPMs from oss.oracle.com, which could be done with --enable-download, an intentionally undocumented option which users are free to try at their own peril :)