Bug#953105: gtk-update-icon-cache does not produce reproducible results on 32-bit architectures

[Orians, Jeremiah (DTMB)]

> But it seems odd that the 32-bit architectures would produce 
> unreproducible caches when the 64-bit version is reproducible.
Why?
Even such things as alignment in malloc results in different behavior between x86 and amd64
For example this function is reproducible on AMD64 but not on x86
https://github.com/oriansj/mes-m2/blob/master/mes_posix.c#L31

Changing the 12 to 13 works around that subtle difference between the 2 architectures.
- Jeremiah