firebird: Fix build by using gcc5

dezgeg · dezgeg · commit 62eeec7486b3 · 2017-09-13T14:43:41.000+03:00
https://hydra.nixos.org/build/59941948 (cherry picked from commit c78c565)
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
@@ -11252,7 +11252,7 @@ with pkgs;
 
   fingerd_bsd = callPackage ../servers/fingerd/bsd-fingerd { };
 
-  firebird = callPackage ../servers/firebird { icu = null; };
+  firebird = callPackage ../servers/firebird { icu = null; stdenv = overrideCC stdenv gcc5; };
   firebirdSuper = callPackage ../servers/firebird { superServer = true; };
 
   fleet = callPackage ../servers/fleet { };
