remove dead case in gethostbyname2_r

this case statement was accidently left behind when this function
was refactored in commit e8f39ca4898237cf71657500f0b11534c47a0521.
diff --git a/src/network/gethostbyname2_r.c b/src/network/gethostbyname2_r.c
index 5c1cae9..fc89487 100644
--- a/src/network/gethostbyname2_r.c
+++ b/src/network/gethostbyname2_r.c
@@ -34,8 +34,6 @@
 	case EAI_SYSTEM:
 		*err = NO_RECOVERY;
 		return errno;
-	case 0:
-		break;
 	}
 
 	h->h_addrtype = af;