Log Message:
Import avr-libc-1.7.1 as wip/avr-libc, as an update for cross/avr-libc 1.6.7.

avr-libc -- a C and math library for the Atmel AVR controller family

This library implements a subset of common C library functions, some
Atmel AVR specific additions (like handling AVR's IO facilities,
EEPROM etc.), as well as a 32-bit floating point math library (-lm).

Everything is designed and implemented to cooperate with avr-gcc and
avr-binutils.

Please note that this is currently work-in-progress.  Documentation
is becoming embedded into the source code which will hopefully get
it more complete and up-to-date.  Some parts of the current library
have proven to be not all that useful (e. g. timer_enable_int())
so they might be removed in a future version.

For the time being, some older documentation (more complete but
somewhat out of date) is being installed as well.