Divide by 0 undefined in C99

[thatcosmonaut]

The C99 spec states that

The result of the / operator is the quotient from the division of the first operand by the second; the result of the % operator is the remainder. In both operations, if the value of the second operand is zero, the behavior is undefined.

In qoaconv.c L270:

double psnr = 1.0/0.0;

This refuses to compile on some compilers like MSVC.

Changing 1.0/0.0 to the INFINITY macro seems to work fine.