cdpr: pull patch pending upstream inclusion for -fno-common

Without the change build fails agains -fno-common toolchains as:

    ld: /build/cct3qrT9.o:(.bss+0x0): multiple definition of `handle'; /build/cc4dJNO8.o:(.bss+0x0): first defined here
    ld: /build/cct3qrT9.o:(.bss+0x8): multiple definition of `cdprs'; /build/cc4dJNO8.o:(.bss+0x8): first defined here
    ld: /build/cct3qrT9.o:(.bss+0xc): multiple definition of `timeout'; /build/cc4dJNO8.o:(.bss+0xc): first defined here
    ld: /build/ccbaP0xb.o:(.bss+0x0): multiple definition of `handle'; /build/cc4dJNO8.o:(.bss+0x0): first defined here
    ld: /build/ccbaP0xb.o:(.bss+0x8): multiple definition of `cdprs'; /build/cc4dJNO8.o:(.bss+0x8): first defined here
    ld: /build/ccbaP0xb.o:(.bss+0xc): multiple definition of `timeout'; /build/cc4dJNO8.o:(.bss+0xc): first defined here

pkgs/tools/networking/cdpr/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchurl, libpcap }:
+{ lib, stdenv, fetchurl, fetchpatch, libpcap }:
 
 stdenv.mkDerivation rec {
   pname = "cdpr";
@@ -8,6 +8,15 @@ stdenv.mkDerivation rec {
     url = "mirror://sourceforge/${pname}/${pname}/${version}/${pname}-${version}.tgz";
     sha256 = "1idyvyafkk0ifcbi7mc65b60qia6hpsdb6s66j4ggqp7if6vblrj";
   };
+  patches = [
+    # Pull fix pending upstream inclusion for gcc-10 compatibility:
+    #  https://sourceforge.net/p/cdpr/bugs/3/
+    (fetchurl {
+      name = "fno-common";
+      url = "https://sourceforge.net/p/cdpr/bugs/3/attachment/0001-cdpr-fix-build-on-gcc-10-fno-common.patch";
+      sha256 = "023cvkpc4ry1pbjd91kkwj4af3hia0layk3fp8q40vh6mbr14pnp";
+    })
+  ];
 
   postPatch = ''
     substituteInPlace Makefile --replace 'gcc' '"$$CC"'