Disable -Werror.

--- a/src/cmd/dist/build.c
+++ b/src/cmd/dist/build.c
@@ -384,7 +384,6 @@ static char *proto_gccargs[] = {
 	"-Wno-unknown-pragmas",
 	"-Wno-switch",
 	"-Wno-comment",
-	"-Werror",
 	"-fno-common",
 	"-ggdb",
 	"-O2",