ART: Add logcat output to signal_dumper

Add option "-l" to log to logcat.

As this requires for simplicity to unify the output path, this
degrades the stderr output readability because of the filename
and so on output from LOG.

Bug: 138868214
Test: manual
Change-Id: I6e6920874e6062cd9c27ccafcf59e63ff2334f77
1 file changed