Fix Arduino Mega 2560 avr-libc issue

 
If you have Arduino Mega 2560 on any updated Linux distro with avr-libc 1.8 you probably have an issue with compiling.
 

Compiler usually fails with this error: attempt to use poisoned "SIG_USART0_RECV"
 
Quick fix is to downgrade to earlier version of avr-libc...
 
Grab older version of avr-libc from Koji:
wget http://kojipkgs.fedoraproject.org//packages/avr-libc/1.7.1/4.fc18/noarch/avr-libc-1.7.1-4.fc18.noarch.rpm
 
Now delete problematic avr-libc 1.8:
sudo rpm -e avr-libc --nodeps
 
And finally install avr-libc 1.7:
sudo yum localinstall avr-libc-1.7.1-3.fc17.noarch.rpm
 
Done.