zathura: disable checkPhase on Darwin

[midchildan]

Motivation for this change

Zathura currently fails to build for Darwin on Hydra during the check phase. Interestingly, the build succeeds on my machine even with the sandbox enabled. Since the resulting binary worked without problems, I just disabled the check phase for Zathura.

Looking at the Hydra build logs, the failure seems to originate from the window system, so there might be some impurities involed.

2021-05-07 13:11:30.458 test_session[70674:7501250] *** Assertion failure in -[_NSCGSWindow setFrame:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/AppKit/AppKit-1561.60.100/CGS.subproj/NSCGSWindow.m:1002
2021-05-07 13:11:30.523 test_session[70674:7501250] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid parameter not satisfying: CGRectContainsRect(CGRectMake((CGFloat)INT_MIN, (CGFloat)INT_MIN, (CGFloat)INT_MAX - (CGFloat)INT_MIN, (CGFloat)INT_MAX - (CGFloat)INT_MIN), frame)'

ZHF: #122042
Failing build: https://hydra.nixos.org/build/142613284

ping @NixOS/nixos-release-managers

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.