Wrapping signed arithmetic is undefined behavior

[Lithrein]

tacle-bench/bench/sequential/adpcm_enc/adpcm_enc.c

Line 242 in 6400092

diff = ( diff * ( -( rad * rad ) ) ) / ( ( 2 * inc ) * ( 2 * inc + 1 ) );

This line needs -fwrapv otherwise modern compilers could optimize it wrongly.