build: add a "user" arch to allow the kernel to run as a program on the host machine

libc/string/memchr.c

@@ -1,10 +1,10 @@
 #include <stddef.h>
 
-const void *memchr(const void *ptr, int value, size_t num) {
+void *memchr(const void *ptr, int value, unsigned long num) {
     const unsigned char *buf = ptr;
     unsigned char val = value;
 
-    for (size_t i = 0; i < num; i++) {
+    for (unsigned long i = 0; i < num; i++) {
         if (buf[i] == val) {
             return (void *)(buf + i);
         }