make the array of registers to use depending on wheter we have an FP or not, and which register we have as FP

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25758 3ad0048d-3df7-0310-abae-a5850022a9f2
set up register A6 to be saved as well. this will only happen in case A6 is not used as framepointer

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25759 3ad0048d-3df7-0310-abae-a5850022a9f2