xannotate: pull patch pending upstream inclusion for -fno-common toolchain support

Without the change build fails against upstream gcc-10 as:

ld: process.o:/build/source/src/process.h:26: multiple definition of
`child'; backend.o:/build/source/src/process.h:26: first defined here

pkgs/tools/X11/xannotate/default.nix

···
-{lib, stdenv, fetchFromBitbucket, libX11}:
+{lib, stdenv, fetchFromBitbucket, fetchpatch, libX11}:
 stdenv.mkDerivation rec {
   pname = "xannotate";
   version = "20150301";
···
     sha256 = "02jy19if0rnbxvs6b0l5mi9ifvdj2qmv0pv278v9kfs0kvir68ik";
   };
 
+  patches = [
+    # Pull patch pending upstream inclusion for -gno-common tollchains:
+    #   https://github.com/blais/xannotate/pull/1
+    (fetchpatch {
+      name = "fno-common.patch";
+      url = "https://github.com/blais/xannotate/commit/ee637e2dee103d0e654865c2202ea1b3af2a20d6.patch";
+      sha256 = "1lw22d5qs1bwp53l332yl3yypfvwrbi750wp7yv90nfn3ia0xhni";
+    })
+  ];
+
   buildInputs = [ libX11 ];
 
   meta = {
···
     license = lib.licenses.gpl2Plus ;
     maintainers = [lib.maintainers.raskin];
     platforms = lib.platforms.linux;
-    homepage = "https://bitbucket.org/blais/xannotate";
+    homepage = "https://github.com/blais/xannotate";
   };
 }