patch to make libyaml compile in visual studio

[roel _ dot _ vanhout _ at _ gmail _ dot _ com]

2 issues:

• pointer arithmetic on void*'s is a gcc-ism. I 'solved' it by casting them all to a unsigned char (typedef'd), I'm not sure if a unsigned char is guaranteed to be the same size as a void* on all architectures - it worked on 32-bit Windows, FWIW.

• A shorthand struct assignment didn't work, I'm not sure if it's valid C or not but whatever, by writing it out in full it compiled ok.

[xi]

Thanks for the patch. Applied in [239].