Add out-of-bounds check

[tygyh]

The size of the buffer from size is used as an array index. This value could be one larger than the last possible index of the array, causing a buffer overread.

[CLAassistant]

All committers have signed the CLA.

[HansKristian-Work]

When is this case ever hit? Does it fix a concrete bug?

[tygyh]

Does it fix a concrete bug?

None which I know of. I tried to fix this since this project is a dependency for a project I'm working on and I wanted to fix it at the root.

[HansKristian-Work]

None which I know of. I tried to fix this since this project is a dependency for a project I'm working on and I wanted to fix it at the root.

I'm not comfortable adding arbitrary code like this when it doesn't solve a concrete problem in SPIRV-Cross. An assert() for being in-range would be acceptable, but actual range-checking should be done on the outside.