Provide memcpy for compatibility with older versions of gcc

defs.h

@@ -124,6 +124,7 @@ void            popcli();
 // string.c
 int             memcmp(const void*, const void*, uint);
 void*           memmove(void*, const void*, uint);
+void*           memcpy(void*, const void*, uint);
 void*           memset(void*, int, uint);
 char*           safestrcpy(char*, const char*, int);
 int             strlen(const char*);

string.c

@@ -44,6 +44,12 @@ memmove(void *dst, const void *src, uint n)
   return dst;
 }
 
+void*
+memcpy(void *dst, const void *src, uint n)
+{
+  return memmove(dst, src, n);
+}
+
 int
 strncmp(const char *p, const char *q, uint n)
 {

user.h

@@ -26,6 +26,7 @@ int sleep(int);
 int stat(char*, struct stat*);
 char* strcpy(char*, char*);
 void *memmove(void*, void*, int);
+void *memcpy(void*, void*, int);
 char* strchr(const char*, char c);
 int strcmp(const char*, const char*);
 void printf(int, char*, ...);