QmakeProject: Don't deny deployment to not precisely known targets

Fall back to what we do for Windows/Linux/BSD and the rest of
Unix anyway.

The target architecture/os detection process is conceptually
not precise. Refusing to do anything at all, including steps like
copying files which do not depend on precise architecture data
anyway, is overshooting.

Change-Id: Ic6c98c4dac5fe4a625149be558c8b02440f8fdbc
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>

src/plugins/qmakeprojectmanager/qmakeproject.cpp

@@ -1659,16 +1659,11 @@ QString QmakeProject::executableFor(const QmakeProFileNode *node)
             break;
         }
         // else fall through
-    case ProjectExplorer::Abi::WindowsOS:
-    case ProjectExplorer::Abi::LinuxOS:
-    case ProjectExplorer::Abi::BsdOS:
-    case ProjectExplorer::Abi::UnixOS: {
+    default: {
         QString extension = node->singleVariableValue(TargetExtVar);
         target = ti.target + extension;
         break;
     }
-    default:
-        return QString();
     }
     return QDir(destDirFor(ti)).absoluteFilePath(target);
 }