pommed_light: pull fix pending upstream inclusion for -fno-common toolchains

Without the change builds fails on upstream gcc-10 as:

    ld: mactel/nv8600mgt_backlight.o:/build/pommed-light/pommed/mactel/nv8600mgt_backlight.c:50: multiple definition of
      `lcd_bck_info'; sysfs_backlight.o:/build/pommed-light/pommed/sysfs_backlight.c:124: first defined here

pkgs/os-specific/linux/pommed-light/default.nix

@@ -1,5 +1,6 @@
 { lib, stdenv
 , fetchFromGitHub
+, fetchpatch
 , pciutils
 , libconfuse
 , alsa-lib
@@ -20,6 +21,16 @@ stdenv.mkDerivation rec {
     sha256 = "18fvdwwhcl6s4bpf2f2i389s71c8k4g0yb81am9rdddqmzaw27iy";
   };
 
+  patches = [
+    # Pull fix pending upstream inclusion for -fno-common toolchain support:
+    #   https://github.com/bytbox/pommed-light/pull/38
+    (fetchpatch {
+      name = "fno-common.patch";
+      url = "https://github.com/bytbox/pommed-light/commit/5848b49b45a9c3ab047ebd17deb2162daab1e0b8.patch";
+      sha256 = "15rsq2i4rqp4ssab20486a1wgxi2cp87b7nxyk9h23gdwld713vf";
+    })
+  ];
+
   postPatch = ''
     substituteInPlace pommed.conf.mactel --replace /usr $out
     substituteInPlace pommed.conf.pmac --replace /usr $out