Fix stale comment about XSAFECOPY (now uses strlcpy, not strncpy)

src/xpdev/gen_defs.h

@@ -439,7 +439,7 @@ typedef struct {
 #define SAFECOPY(dst,src)                   strlcpy(dst,src,sizeof(dst))
 #endif
 
-/* Extra-safe SAFECOPY doesn't pass NULL-pointer to strncpy */
+/* Extra-safe SAFECOPY doesn't pass NULL-pointer to strlcpy */
 #ifdef _DEBUG
 #define XSAFECOPY(dst,src) do { \
 	static_assert(sizeof(dst) != sizeof(void*), "SAFECOPY() on pointer-sized dst, use strlcpy"); \