Update platform.txt for gcc-4.8.1; board menu heading.
Update platform.txt for gcc-4.8.1; board menu heading.

rrobinet/Cosa,jeditekunum/Cosa,dansut/Cosa,mikaelpatel/Cosa,jeditekunum/Cosa,kc9jud/Cosa,rrobinet/Cosa,rrobinet/Cosa,mikaelpatel/Cosa,mikaelpatel/Cosa,dansut/Cosa,jeditekunum/Cosa,rrobinet/Cosa,dansut/Cosa,dansut/Cosa,kc9jud/Cosa,mikaelpatel/Cosa,jeditekunum/Cosa,kc9jud/Cosa,kc9jud/Cosa