event_pipe, test: explicitly ignore write() return value

Some compilers are very picky, but we really aren't interested in the
return value.

test/run_encoder.c

@@ -36,8 +36,9 @@ encoder_to_stdout(struct encoder *encoder)
 	size_t length;
 	static char buffer[32768];
 
-	while ((length = encoder_read(encoder, buffer, sizeof(buffer))) > 0)
-		write(1, buffer, length);
+	while ((length = encoder_read(encoder, buffer, sizeof(buffer))) > 0) {
+		G_GNUC_UNUSED ssize_t ignored = write(1, buffer, length);
+	}
 }
 
 int main(int argc, char **argv)