rocclr: Re-enable support for gfx8

The patch has been floating around for a while and I think it’s applied
for some distributions.

I tested OpenCL on gfx8 and gfx10 and it's both working with this patch.

pkgs/development/libraries/rocclr/default.nix

@@ -1,5 +1,6 @@
 { lib, stdenv
 , fetchFromGitHub
+, fetchpatch
 , writeScript
 , rocm-comgr
 }:
@@ -15,6 +16,16 @@ stdenv.mkDerivation rec {
     hash = "sha256-SFWEGKffhuiTE7ICbkElVV5cldXu4Xbwvjb6LiNmijA=";
   };
 
+  patches = [
+    # Enable support for gfx8 again
+    # See the upstream issue: https://github.com/RadeonOpenCompute/ROCm/issues/1659
+    # And the arch patch: https://github.com/rocm-arch/rocm-arch/pull/742
+    (fetchpatch {
+      url = "https://raw.githubusercontent.com/John-Gee/rocm-arch/d6812d308fee3caf2b6bb01b4d19fe03a6a0e3bd/rocm-opencl-runtime/enable-gfx800.patch";
+      hash = "sha256-59jFDIIsTTZcNns9RyMVWPRUggn/bSlAGrky4quu8B4=";
+    })
+  ];
+
   prePatch = ''
     substituteInPlace device/comgrctx.cpp \
       --replace "libamd_comgr.so" "${rocm-comgr}/lib/libamd_comgr.so"