Detect and branch on presence of SLEEP_SMODE<n>_bm for xmegas, instead of assuming 3 bits always.

git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2458 1084037a-409f-4a99-8160-1a4b3577d4c1
Add a note section containing device info to the crt file.

git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2459 1084037a-409f-4a99-8160-1a4b3577d4c1