Change chdir system call # to match linux

useful for apex

Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>

sys/src/sysconf.json

@@ -38,7 +38,7 @@
 			"Args": [
 				"char*"
 			],
-			"Id": 4099,
+			"Id": 80,
 			"Name": "chdir",
 			"Ret": [
 				"int32_t"