Append one array to another
#include <array.h>
void array_cat(array* x,array* y);
array x; array y; array_cat(&x,&y);
array_cat appends y to x; i.e., it changes x, allocating more space if necessary, so that the initialized bytes in x are the previously initialized bytes in x followed by a copy of the initialized bytes in y.
If x has failed, array_cat has no effect.
If y has failed, array_cat switches x to have failed.
If not enough memory is available, array_cat switches x to have failed.