Fix iOS builds

Other tools in tools could theoretically be using QML modules, so qt.prf
tries to use the qmlimportscanner on them. That means we have to build it
before all the other tools.

Change-Id: I5ee49d0f3f4f3bf73183a6be9414c8d0e926bdf1
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>
Fix ARM thumb2 mode detection

__TARGET_ARCH_THUMB may not always be defined, but __thumb2__ for example
is also a good indicator that we can generated and run thumb2 code and
thus enable the JIT.

Change-Id: I987d0af5883d9bb844c4c99a0691a12aedc94ff5
Reviewed-by: Lars Knoll <lars.knoll@digia.com>