Fix indexing for platforms where char size is larger than a byte

[GMMan]

On platforms where the minimum memory access size is larger than a byte (case in point, μ'nSP where each address refers to one 16-bit word rather than a byte), indexing would never work due to the index buffer being initialized improperly. Instead of each element being initialized to -1 as would typically happen on a system with byte sized access, it gets initialized to 255. This breaks the indexing logic and causes it to go into an infinite loop.

This patch changes the initializer from 0xff to -1, so depending on the platform it should always initialize the entire array with -1. On byte access systems, memset() will truncate the -1 to 0xff as per standard, which results in the same desired behavior.

[silentbicycle]

Thanks, this will be cherry-picked to the develop branch for the next versioned release.