a bug fix in fec auto tuning

1. fixed a bug in fec tuning when fec parameters on client & server side are set differently. xtaci/kcp-go@ceebe17

$ go version
go version go1.21.3 linux/amd64

$ date
Thu Oct 12 23:29:14 CST 2023

$ ./build-release.sh
Setting GO111MODULE to on
d274eb50ab0f8b3dda42d57198e009f6abfcc850  kcptun-linux-amd64-20231012.tar.gz
ecd4d86cd74eda7c6fc3483f90dcaf20a7780c51  kcptun-darwin-amd64-20231012.tar.gz
b370c50569b29c22b635f8e64a6d2b77b9a5974e  kcptun-windows-amd64-20231012.tar.gz
6c21e6ddf615b638ee829a2626248f94e30b3b53  kcptun-freebsd-amd64-20231012.tar.gz
decef69ae6c42ccd205746c1e29ec12024fa48a9  kcptun-linux-386-20231012.tar.gz
f800492ea1f53c328eda8d2ad9396a9f101e2519  kcptun-windows-386-20231012.tar.gz
db096a27b6240b027f6238f85ef8513188a87d32  kcptun-linux-arm5-20231012.tar.gz
7d357740aafe2b143d7d784efd1c44dc09f2d926  kcptun-linux-arm6-20231012.tar.gz
c2cdc7f67eb6d8a8fbf0aca07ec6ac8ae9feb44f  kcptun-linux-arm7-20231012.tar.gz
c495361807bfcb3533444423a2dfa41a54dcd3b8  kcptun-linux-arm64-20231012.tar.gz
95609a21306b92ed2755cb7177106f14d73f64c5  kcptun-darwin-arm64-20231012.tar.gz
cfa12cf0c8bfe52c2ad7223890cc326089d9683e  kcptun-windows-arm64-20231012.tar.gz
d52cb90291132efa40e4b36482efe5feecc5a272  kcptun-linux-mipsle-20231012.tar.gz
4f90cd0fbaf61ea2b4a97d4c8ea6b074eea3a753  kcptun-linux-mips-20231012.tar.gz