adb: fix bugreport status line.

The status line char* was getting converted to bool and used as the
compression argument, and the actual status line was defaulting to
nullptr. This didn't actually really change anything, since we only use
the name during transfer, and not for the final message at the end, so
the output is slightly uglier for 50 milliseconds.

This also had the side effect of turning on compression for the
already-compressed bugreport zip, which costs a bit of throughput with
brotli.

Bug: https://issuetracker.google.com/150827486
Test: adb bugreport foo.zip
Change-Id: I74bed9c09442c655a956eb1e8318c0123632ef4c