spirv-headers: backport patch for SPIRV translator w/ LLVM 22

spirv-llvm-translator needs new definitions to compile with LLVM 22,
and there isn't a release containing this patch yet, so we must
backport it.

Additionally, switch spirv-llvm-translator to use `srcOnly` instead
of `.src` so that the new patch is picked up.

pkgs/by-name/sp/spirv-headers/package.nix

@@ -24,6 +24,12 @@ stdenv.mkDerivation (finalAttrs: {
       url = "https://github.com/KhronosGroup/SPIRV-Headers/commit/1a22b167081842915a1c78a0b5b5a353a23284aa.diff";
       hash = "sha256-XUHfPHnk7bWK4vnozfW/84vaZN+rbFJUZSa6Og8GUAU=";
     })
+    # Backport new predicated load/store instructions, needed by spirv-llvm-translator
+    # Not in any tagged releases yet, should exist in the next release after 1.4.350.1.
+    (fetchpatch {
+      url = "https://github.com/KhronosGroup/SPIRV-Headers/commit/b8a32968473ce852a809b9de5f04f02a5a9dfa78.patch";
+      hash = "sha256-59jmN28ifEhAxySXCpuGZ62jo1WVsRPnVosK8X4yrjM=";
+    })
   ];
 
   nativeBuildInputs = [ cmake ];

pkgs/by-name/sp/spirv-llvm-translator/package.nix

@@ -1,6 +1,7 @@
 {
   lib,
   stdenv,
+  srcOnly,
   fetchFromGitHub,
   fetchpatch,
   cmake,
@@ -84,7 +85,7 @@ stdenv.mkDerivation {
     "-DLLVM_SPIRV_BUILD_EXTERNAL=YES"
     # RPATH of binary /nix/store/.../bin/llvm-spirv contains a forbidden reference to /build/
     "-DCMAKE_SKIP_BUILD_RPATH=ON"
-    "-DLLVM_EXTERNAL_SPIRV_HEADERS_SOURCE_DIR=${spirv-headers.src}"
+    "-DLLVM_EXTERNAL_SPIRV_HEADERS_SOURCE_DIR=${srcOnly spirv-headers}"
   ]
   ++ lib.optional (
     lib.toInt llvmMajor >= 19