Add windows detection when executing arc

[colin-harms]

This is in relation to #244
If the ApplyPatchTask is being instantiated as part of a build, it will check the JVM's "os.name" property to see if it's Windows. The "startsWith Windows" logic was lifted from common-lang's SystemUtils.IS_WINDOWS

I've been trying to get a proper unit test going for this, but because Computer.currentComputer() checks to see if the current thread is a Hudson Executor, it will fail in normal unit tests (as in ApplyPatchTaskTest)

If it runs as a build in the PhabricatorBuildWrapperTest class, it will actually check the values of "os.name", but I don't want to override it as part of the test, since it sets it globally across the jvm that is running the test.

I'm open to suggestions to create a lightweight test for this. I'm not very familiar with Jenkins plugin development, but I did run into that "arc" vs "arc.bat" problem, and this change solved it.

[CLAassistant]

All committers have signed the CLA.

[coveralls]

Coverage decreased (-0.2%) to 90.138% when pulling b371498 on colin-harms:master into d24c091 on uber:master.

[kageiit]

@colin-harms can you please sign the CLA?

[withinfocus]

@colin-harms can you respond to the above? We'd love to get this included for our own purposes as we're experiencing the same issue with multi-platform builds.

[colin-harms]

@withinfocus I signed it a while ago, I'm not sure why it's not recognising it.

[kageiit]

I closed and re-opened the PR for the checks to trigger again

[withinfocus]

@colin-harms Maybe go to https://cla-assistant.io/uber/phabricator-jenkins-plugin?pullRequest=270 again and see if it sticks?

[colin-harms]

I've tried chrome, chrome incognito, firefox ( which I never use ), signing out of CLA and back in. The signing page always switches from "Please sign ... " to "You have signed ... ".
Not sure what I can do to push this forward

[withinfocus]

@kageiit can this be manually resolved then?

[withinfocus]

Bump on this one. Would love for it to come through in the next plugin release. Can someone at Uber commandeer this and merge it themselves?

[kageiit]

@briankhsieh Any idea why the CLA is not being recognized?

[kageiit]

@withinfocus can you please resolve the conflicts?

[bhenhsi]

Hi can you try sign the CLA with username @ch4rms ?

[ch4rms]

It finally worked!!
IIRC, the last time I tried the CLA form, it wasn't prompting me for my details or showing me the check box (it's been a while)

[kageiit]

@ch4rms can you please resolve the merge conflicts?

[ch4rms]

Thanks @kageiit I was just fixing it up when I got the email notification :)