title: gcc, make: how to disable fail on warning?
body: <p>I'm trying to build gcc for use with an AVR micro controller and avr-ada, and I've hit a roadblock caused by my regular compiler being too picky about the version I needed for the AVR.  I get the following warning, which in turn causes the gcc or make to report an error:</p>
  
  <pre><code>gcc -c -g -O2 -gnatpg -gnata -nostdinc -I- -I. -Iada 
    -I../../gcc/ada ../../gcc/ada/exp_ch5.adb -o ada/exp_ch5.o
  exp_ch5.adb:177:16: warning: function "Has_Address_Clause" is not referenced
  make[2]: *** [ada/exp_ch5.o] Error 1
  make[1]: *** [all-gcc] Error 2
  make: *** [all] Error 2
  </code></pre>
  
  <p>Is there a way to instruct gcc or make to not fail on warnings?</p>