RunCMake: Ignore cmakexbuild warnings in tests
Encountered on master-MacOSX10.4.11i386-Xcode (dashmacmini2.kitware.com)
Expected stderr to match:
expect-err> ^$
Actual stderr:
actual-err> Hit xcodebuild bug : /bin/sh: /Users/kitware/Dashboards/My Tests-MacOSX10.4.11i386-Xcode/CMakeMaster-build/Tests/RunCMake/CrosscompilingEmulator/AddCustomCommand-build/AddCustomCommand.build/Debug/ZERO_CHECK.build/Script-71CF34B67E0B4D0AAAA1463A.sh: /bin/sh: bad interpreter: Text file busy