[PING^1][patch][avr] New option -nodevicespecs to omit -specs=... in self specs.

[Georg-Johann Lay]

Ping #1

Hi, currently device support in avr-gcc is accomplished by injecting a specs file my means of -specs=... in dirver self specs.

This patch adds a new avr driver option to omit the addition of respective -specs option so give the user more freedom.

Ok to apply?

Johann

    * config/avr/avr.opt (-nodevicespecs): New driver option.
    * config/avr/driver-avr.c (avr_devicespecs_file): Only issue
    "-specs=device-specs/..." if that option is not set.
    * doc/invoke.texi (AVR Options) <-nodevicespecs>: Document.