bug #40003: cast expression to required destination type to avoid inefficient code by gcc

git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2419 1084037a-409f-4a99-8160-1a4b3577d4c1
bug #42024: fix typo in avrtiny macro

git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2420 1084037a-409f-4a99-8160-1a4b3577d4c1
bug #40206: write to SPL and then SPH for xmega SP initialization (consistent with what compiler does for function prologues)

git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2421 1084037a-409f-4a99-8160-1a4b3577d4c1