Fix deployment target autotest.
Fix deployment target autotest.

Older versions of Clang (such as that which is included in Xcode 5.1.x)
do not always expand the minimum operating system version number in
-*_version_min flags passed to the linker to three components as newer
versions do. Thus, only check for the first two version components.

Change-Id: Ia666aad44836f62311869affc3f4b26eb53ff15b
Reviewed-by: Christian Kandeler <3aa99dcdd3f0cac61fb81c2a11771c0cc2497607@theqtcompany.com>

qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,qt-labs/qbs,qt-labs/qbs,qt-labs/qbs