Support for Fedora Copr

[lzaoral]

I have created a testing copr-repository. Feel free to fork the COPR project, but don't forget to change the source git repository and source branch and merge #326 in advance. It can also be configured to behave like a CI, so that it rebuilds the packages with each new commit in given branch. That can be set up in the copr repository settings.

The current build status is following, only systems with LLVM versions supported by dg are listed. I have also tried aarch64 just for curiosity and it seems to work just fine.

System	aarch64	x86_64	x86
Fedora 31	OK	OK	OK
Fedora 32	OK	OK	OK
Fedora 33	OK	OK	OK
Fedora Rawhide	OK	OK	OK
Fedora ELN - currently broken in Copr (not caused by dg)	-	-	-
CentOS stream	OK	OK	-
Epel for CentOS 8	OK	OK	-
Mageia 7	FAIL	FAIL	FAIL
Mageia Cauldron	FAIL	FAIL	FAIL
openSuse Leap 15.1	FAIL	FAIL	-
openSuse Leap 15.2	FAIL	FAIL	-
openSuse Tumbleweed	FAIL	FAIL	FAIL

• - = not available
• OK = Tests pass

• Mageia and openSuse fail with linking errors
• 32-bit Fedora builds with several warnings, but tests fail.
• openSuse does not provide llvm-static and dg does not support dynamic linking with LLVM

Update: 29/10/2020

[lzaoral]

The Mageia linking errors are caused by the --as-needed --no-undefined flags for linker:

• https://wiki.mageia.org/en/Underlinking_issues_in_packaging
• https://wiki.mageia.org/en/Overlinking_issues_in_packaging

As far as I can tell, Suse uses these flags by default for rpm packages as well.

[lzaoral]

It seems that only --no-undefined is the culprit as Fedora uses --as-needed by default in rpm builds and everything is fine.