iOS/CMake: Fix running non-Xcode targets and targets in subdirectories

Improve support for running iOS bundle built with CMake introduced in
3a294f670d.
Currently it supports only Xcode generator and does not work if target is
created in a subdirectory.

This patch adds support for non-Xcode generators (tested with Ninja) and
targets created in a subdirectories with any generators.

The solution is not pretty due to the need to keep qmake compatibility.
Would be glad to refactor if there's more correct approach.

Change-Id: Ieaf7e3186ab55cadc643d9bd3d94442f9ac72228
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/ios/iosconstants.h

@@ -47,6 +47,7 @@ const char IOS_DEPLOY_STEP_ID[] = "Qt4ProjectManager.IosDeployStep";
 
 const char IosTarget[] = "IosTarget"; // QString
 const char IosBuildDir[] = "IosBuildDir"; // QString
+const char IosCmakeGenerator[] = "IosCmakeGenerator";
 
 const quint16 IOS_DEVICE_PORT_START = 30000;
 const quint16 IOS_DEVICE_PORT_END = 31000;