crash-reporter: add support for device coredump

Copy the device coredump file to /var/spool/crash directory when
udev event "devcoredump" is detected. Also include the last 50 lines
of /var/log/messages and /var/log/net.log in the coredump file for
debugging purpose. Only perform the collection if feedback is allowed
(metrics are enabled) or the device is running a developer image.

By default, crash-reporter will not upload device coredumps to the crash
server. The user can enable device coredumps upload via a to-be-added
crosh command, which should only be done at the direction of CrOS engineers.

BUG=chromium:464872
TEST=USE="asan clang" FEATURES=test emerge-$BOARD crash-reporter
Manual Test:
1. Trigger wifi firmware error on a Clapper running developer image by
   running following command:
   "echo 1 > /sys/kernel/debug/iwlwifi/0000\:01\:00.0/iwlmvm/fw_restart"
2. Verify there is a device coredump file in "/var/spool/crash/"
   "devcoredump_iwlwifi*.devcore", as well as the additional log file
   ".log" and the meta file ".meta".

Change-Id: Ic4cf67d4b5715a6f422505f409276d1261b7d51f
Reviewed-on: https://chromium-review.googlesource.com/257091
Reviewed-by: Zeping Qiu <[email protected]>
Commit-Queue: Zeping Qiu <[email protected]>
Tested-by: Zeping Qiu <[email protected]>
Reviewed-by: Mike Frysinger <[email protected]>
diff --git a/99-crash-reporter.rules b/99-crash-reporter.rules
index 57a71ca..aea5b1c 100644
--- a/99-crash-reporter.rules
+++ b/99-crash-reporter.rules
@@ -3,3 +3,4 @@
 ACTION=="change", SUBSYSTEM=="i2c", DRIVER=="cyapa", ENV{ERROR}=="1", RUN+="/sbin/crash_reporter --udev=SUBSYSTEM=i2c-cyapa:ACTION=change"
 # For detecting Atmel trackpad/touchscreen issue. Passing into crash_reporter SUBSYSTEM=i2c-atmel_mxt_ts since crash_reporter does not handle DRIVER string.
 ACTION=="change", SUBSYSTEM=="i2c", DRIVER=="atmel_mxt_ts", ENV{ERROR}=="1", RUN+="/sbin/crash_reporter --udev=SUBSYSTEM=i2c-atmel_mxt_ts:ACTION=change"
+ACTION=="add", SUBSYSTEM=="devcoredump", RUN+="/sbin/crash_reporter --udev=SUBSYSTEM=devcoredump:ACTION=add:KERNEL_NUMBER=%n"