* clz is only available on thumb2/arm

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25416 3ad0048d-3df7-0310-abae-a5850022a9f2
* check cputhumb/cputhumb2 to detect instruction set

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25417 3ad0048d-3df7-0310-abae-a5850022a9f2
* do shifts for sign/zero extensions correctly

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25418 3ad0048d-3df7-0310-abae-a5850022a9f2