avoid EPROTO in case not there (Tim Wiess)

src/cmd/9pfuse/errstr.c

diff --git a/src/cmd/9pfuse/errstr.c b/src/cmd/9pfuse/errstr.c
index 9b13286..a51e337 100644
--- a/src/cmd/9pfuse/errstr.c
+++ b/src/cmd/9pfuse/errstr.c
@@ -41,7 +41,11 @@
 	{ "illegal", EINVAL },
 	{ "read-only", EROFS },
 	{ "read only", EROFS },
+#ifdef EPROTO
 	{ "proto", EPROTO },
+#else
+	{ "proto", EINVAL },
+#endif
 	{ "entry", ENOENT },
 };