* internal/testlog: print file+line number of log call in test log
This changes the unit test logger to print the actual file and line
number of the logging call instead of "testlog.go:44".
Output of 'go test -v -run TestServerListen ./p2p' before this change:
=== RUN TestServerListen
--- PASS: TestServerListen (0.00s)
testlog.go:44: DEBUG[01-08|15:16:31.651] UDP listener up addr=127.0.0.1:62678
testlog.go:44: DEBUG[01-08|15:16:31.651] TCP listener up addr=127.0.0.1:62678
testlog.go:44: TRACE[01-08|15:16:31.652] Accepted connection addr=127.0.0.1:62679
And after:
=== RUN TestServerListen
--- PASS: TestServerListen (0.00s)
server.go:868: DEBUG[01-08|15:25:35.679] TCP listener up addr=127.0.0.1:62712
server.go:557: DEBUG[01-08|15:25:35.679] UDP listener up addr=127.0.0.1:62712
server.go:912: TRACE[01-08|15:25:35.680] Accepted connection addr=127.0.0.1:62713
* internal/testlog: document use of t.Helper
