bug #39049: Add clock_prescale_set and get function/ macro for tiny 4/5/9/10/20 and 40 devices

git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2422 1084037a-409f-4a99-8160-1a4b3577d4c1
bug #37103: Add wdt_enable and wdt_disable macros for ATtiny4/5/9/10/20/40 devices

git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2423 1084037a-409f-4a99-8160-1a4b3577d4c1
bug #35498: fix a typo in util/setbaud.h

git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2424 1084037a-409f-4a99-8160-1a4b3577d4c1