ref: 2db3642b8d3b871c6f9d1f4e3204b2f44fc4b79f dir: /sys/src/ape/lib/ap/gen/strcat.c/
#include <string.h> char* strcat(char *s1, const char *s2) { strcpy(strchr(s1, 0), s2); return s1; }