openbgpd: add -fcommon workaround

Workaround build failure on -fno-common toolchains like upstream
gcc-10. Otherwise build fails as:

ld: bgpd-rde_peer.o:/build/source/src/bgpd/bgpd.h:133: multiple definition of `bgpd_process';
bgpd-bgpd.o:/build/source/src/bgpd/bgpd.h:133: first defined here

+6
+6
pkgs/servers/openbgpd/default.nix
··· 35 35 ./autogen.sh 36 36 ''; 37 37 38 + # Workaround build failure on -fno-common toolchains like upstream 39 + # gcc-10. Otherwise build fails as: 40 + # ld: bgpd-rde_peer.o:/build/source/src/bgpd/bgpd.h:133: multiple definition of `bgpd_process'; 41 + # bgpd-bgpd.o:/build/source/src/bgpd/bgpd.h:133: first defined here 42 + NIX_CFLAGS_COMPILE = "-fcommon"; 43 + 38 44 meta = with lib; { 39 45 description = 40 46 "A free implementation of the Border Gateway Protocol, Version 4. It allows ordinary machines to be used as routers exchanging routes with other systems speaking the BGP protocol";