Append an integer to a stralloc
#include <stralloc.h>
int stralloc_catulong0(stralloc* sa, unsigned long int in, size_t n);
stralloc_catulong0 converts in to a string using fmt_ulong0 and appends the result to sa, allocating memory as necessary.
If there was a memory allocation failure, stralloc_catulong0 returns 0, else 1.
1 for success, 0 on memory allocation failure.