function signature fix: add const qualifier to mempcpy src arg

include/string.h

@@ -75,7 +75,7 @@ char *strchrnul(const char *, int);
 char *strcasestr(const char *, const char *);
 char *strsep(char **, const char *);
 void *memrchr(const void *, int, size_t);
-void *mempcpy(void *, void *, size_t);
+void *mempcpy(void *, const void *, size_t);
 #endif
 
 #ifdef __cplusplus

src/string/mempcpy.c

@@ -1,6 +1,6 @@
 #include <string.h>
 
-void *mempcpy(void *dest, void *src, size_t n)
+void *mempcpy(void *dest, const void *src, size_t n)
 {
 	memcpy(dest, src, n);
 	return (char *)dest + n;