Save server logs for tests with a .testconfig
Save server logs for tests with a .testconfig

Summary:
The runtests script uses flow start, which outputs to a log file. Any printf
debugging gets directed to the log file, but we can't see where it is. This diff
uses the --log-file flag, so the log file is saved to the test directory.

The log file is created and cleaned up by the same rules as the .exp, .out,
.diff files.

Reviewed By: gabelevi

Differential Revision: D4372892

fbshipit-source-id: 01ea7b3c25c6fb6a7258f5a1eb9918ccbe25db52

MichaelDeBoey/flow,mroch/flow,facebook/flow,facebook/flow,gabro/flow,JonathanUsername/flow,gabelevi/flow,JonathanUsername/flow,ylu1317/flow,nmote/flow,AgentME/flow,facebook/flow,MichaelDeBoey/flow,samwgoldman/flow,facebook/flow,facebook/flow,popham/flow,gabelevi/flow,gabelevi/flow,AgentME/flow,gabelevi/flow,gabelevi/flow,samwgoldman/flow,ForbesLindesay/flow,nmote/flow,jamesgpearce/flow,mroch/flow,gabro/flow,mroch/flow,TiddoLangerak/flow,JonathanUsername/flow,ylu1317/flow,popham/flow,TiddoLangerak/flow,fletcherw/flow,mroch/flow,MichaelDeBoey/flow,ForbesLindesay/flow,nmote/flow,ylu1317/flow,popham/flow,jamesgpearce/flow,JonathanUsername/flow,AgentME/flow,ForbesLindesay/flow,TiddoLangerak/flow,TiddoLangerak/flow,nmote/flow,ylu1317/flow,claudiopro/flow,fletcherw/flow,popham/flow,jamesgpearce/flow,gabro/flow,JonathanUsername/flow,gabro/flow,nmote/flow,nmote/flow,ylu1317/flow,facebook/flow,samwgoldman/flow,jamesgpearce/flow,MichaelDeBoey/flow,AgentME/flow,samwgoldman/flow,popham/flow,jamesgpearce/flow,fletcherw/flow,jamesgpearce/flow,jamesgpearce/flow,TiddoLangerak/flow,ForbesLindesay/flow,samwgoldman/flow,claudiopro/flow,gabelevi/flow,gabelevi/flow,gabro/flow,ForbesLindesay/flow,ForbesLindesay/flow,mroch/flow,popham/flow,claudiopro/flow,samwgoldman/flow,nmote/flow,facebook/flow,JonathanUsername/flow,MichaelDeBoey/flow,claudiopro/flow,popham/flow,fletcherw/flow,samwgoldman/flow,gabro/flow,mroch/flow,AgentME/flow,JonathanUsername/flow,fletcherw/flow,mroch/flow,fletcherw/flow,claudiopro/flow