Submitted by Senthil Kumar Selvaraj:
* include/avr/Makefile.am (avr_HEADERS): add xmega.h



git-svn-id: http://svn.savannah.nongnu.org/svn/avr-libc/trunk@2306 1084037a-409f-4a99-8160-1a4b3577d4c1