Adds RPM packaging support on [Fedora Copr](https://copr.fedorainfracloud.org/).
Currently only tested with Fedora 30+.
Supporting for other distributions like RHEL/CentOS/Suse/OpenSuse requires some dependencies that are not in their official repos so it is not covered in this PR.
Build RPMs locally:
``` bash
dnf install -y git mock make
make -f .copr/Makefile srpm # build source RPM
make -f .copr/Makefile rpm # build binary RPM
```
This makefile uses [Mock](https://github.com/rpm-software-management/mock) to build RPMs in a chroot environment. To use a chroot differed from your build distribution, use `RPM_BUILDROOT=<chroot-name>` Makefile variable.
For example, build against Fedora 32 on a CentOS 8 machine:
```bash
make -f .copr/Makefile rpm RPM_BUILDROOT=fedora-32-$(uname -m)
```
Example build: https://copr.fedorainfracloud.org/coprs/yux/v2ray/build/1329864/
