This patch factors out a lot of the basic protocol code: sending OKAY,
sending FAIL, and sending a length-prefixed string.
ADB_TRACE has been non-optional for a long time, so let's just remove
the #ifs.
Also actually build the device tracker test tool (and remove its duplicate).
Bug: http://b/20666660
Change-Id: I6c7d59f18707bdc62ca69dea45547617f9f31fc6
(cherry picked from commit e67f1f87d9)
I keep trying to clean things up and needing std::strings. Might as
well just do this now.
usb_linux_client.c is going to stay as C because GCC isn't smart
enough to deal with the designated initializers it uses (though for
some reason it is in C mode).
The Darwin files are staying as C because I don't have a way to test
that they build.
The Windows files are staying as C because while I can actually build
for them, it's slow and painful.
Change-Id: I75367d29205a9049d34460032b3bb36384f43941
