ART: Null thread_name check for loggings in rare occasions.

Passing null char* to ostream::operator<< is undefined and can cause
a crash (for instance when libc++ is used) instead of printing the log.

Bug: None (crbug.com/531282)
Test: None

Change-Id: Ieb1f0fc50723b06e72b66b1da7b6abe58d5b9a02
1 file changed