* [jenkins] Automatically detect mono bumps and enable device build.
And do this before fetching labels, so that we can skip fetching labels if we
know we're already enabling the device build.
* [tests] Bumping LLVM merits enabling device build and running mtouch + BCL tests.
* [jenkins] Add support for enabling device builds using labels.
* [xharness] Give the iOS MSBuild tests 30 minutes to finish.
* [mtouch tests] Give the BuildTestProject 10 minutes to compile each test case.
Wrench bots build the dontlink test in ~3m40, but that's apparently not enough
for the Jenkins bots (slower bots?), which time out the test after 5 minutes.
So double the timeout to 10 minutes, which will hopefully give the Jenkins
bots enough time to run the test to completion.