pretend test bundle succeeds if no tests ran but exit code was != 0
pretend test bundle succeeds if no tests ran but exit code was != 0

Summary:
This is a fix for the bug where xcodetool would claim that tests failed
even though all tests passed.

```
** RUN-TESTS FAILED: 1517 of 1517 tests passed ** (216447 ms)
```

This is better explained in the comment but...

This was uncovered because a test target had no source files and so
no test binary was created.

When otest would try to run it, it would exit with non-zero status.

In Xcode, they just ignore the non-zero exit status and claim it
succeeded.

We should to do the same.

1yvT0s/xctool,kernandreas/xctool,soundcloud/xctool,modulexcite/xctool,PSPDFKit-labs/xctool,trello/xctool,ekingo/xctool,trello/xctool,bhamiltoncx/xctool,ACChe/xctool,adamjernst/xctool,0xced/xctool,lpios/xctool,theiren46/xctool,dvor/xctool,FiftyThree/xctool,Monits/xctool,AutoScout24/xctool,Monits/xctool,githubdelegate/xctool,SuPair/xctool,adamjernst/xctool,lpios/xctool,kcoons/xctool,yaoxiaoyong/xctool,agreco/xctool,ACChe/xctool,bgertzfield/xctool,lqi/xctool,modulexcite/xctool,yaoxiaoyong/xctool,ekingo/xctool,blighli/xctool,blighli/xctool,bhamiltoncx/xctool,lpios/xctool,facebook/xctool,adamjernst/xctool,lpios/xctool,soundcloud/xctool,bhamiltoncx/xctool,blighli/xctool,leopardpan/xctool,soundcloud/xctool,kernandreas/xctool,jspahrsummers/xctool,lqi/xctool,Monits/xctool,facebook/xctool,soundcloud/xctool,1yvT0s/xctool,facebook/xctool,dvor/xctool,n054/xctool,leopardpan/xctool,ekingo/xctool,SuPair/xctool,kamoljan/xctool,0xced/xctool,blighli/xctool,ACChe/xctool,duk42111/xctool,Monits/xctool,Richardlihui/xctool,n054/xctool,PSPDFKit-labs/xctool,FiftyThree/xctool,kamoljan/xctool,agreco/xctool,kamoljan/xctool,soundcloud/xctool,jspahrsummers/xctool,leopardpan/xctool,githubdelegate/xctool,jspahrsummers/xctool,lqi/xctool,PSPDFKit-labs/xctool,kernandreas/xctool,bgertzfield/xctool,LegNeato/xctool,n054/xctool,kernandreas/xctool,trello/xctool,yaoxiaoyong/xctool,bhamiltoncx/xctool,AutoScout24/xctool,AutoScout24/xctool,1yvT0s/xctool,duk42111/xctool,bhamiltoncx/xctool,modulexcite/xctool,PSPDFKit-labs/xctool,PSPDFKit-labs/xctool,theiren46/xctool,dvor/xctool,FiftyThree/xctool,Richardlihui/xctool,theiren46/xctool,bgertzfield/xctool,Richardlihui/xctool,LegNeato/xctool,kcoons/xctool,1yvT0s/xctool,ACChe/xctool,theiren46/xctool,bhamiltoncx/xctool,leopardpan/xctool,bgertzfield/xctool,facebook/xctool,agreco/xctool,FiftyThree/xctool,adamjernst/xctool,bgertzfield/xctool,soundcloud/xctool,ACChe/xctool,ekingo/xctool,duk42111/xctool,lpios/xctool,lpios/xctool,AutoScout24/xctool,SuPair/xctool,facebook/xctool,n054/xctool,facebook/xctool,LegNeato/xctool,jspahrsummers/xctool,yaoxiaoyong/xctool,n054/xctool,trello/xctool,agreco/xctool,bgertzfield/xctool,LegNeato/xctool,duk42111/xctool,kamoljan/xctool,modulexcite/xctool,n054/xctool,Richardlihui/xctool,SuPair/xctool,ACChe/xctool,githubdelegate/xctool,kcoons/xctool,dvor/xctool,githubdelegate/xctool