cudaPackages.nccl: 2.26.2 -> 2.27.6

nccl 2.27.6 changed its CXXSTD from cpp11 to 14, so the workaround is no
longer required.

2.27 adds a new "symmetric" set of APIs which require their generated
script to have its shebang patched.

pkgs/development/cuda-modules/packages/nccl.nix

@@ -24,10 +24,10 @@ let
     ;
   # versions 2.26+ with CUDA 11.x error with
   # fatal error: cuda/atomic: No such file or directory
-  version = if cudaAtLeast "12.0" then "2.26.2-1" else "2.25.1-1";
+  version = if cudaAtLeast "12.0" then "2.27.6-1" else "2.25.1-1";
   hash =
     if cudaAtLeast "12.0" then
-      "sha256-iLEuru3gaNLcAdH4V8VIv3gjdTGjgb2/Mr5UKOh69N4="
+      "sha256-/BiLSZaBbVIqOfd8nQlgUJub0YR3SR4B93x2vZpkeiU="
     else
       "sha256-3snh0xdL9I5BYqdbqdl+noizJoI38mZRVOJChgEE1I8=";
 in
@@ -74,12 +74,7 @@ backendStdenv.mkDerivation (finalAttrs: {
 
   postPatch = ''
     patchShebangs ./src/device/generate.py
-  ''
-  # CUDA 12.8 uses GCC 14 and we need to bump C++ standard to C++14
-  # in order to work with new constexpr handling
-  + lib.optionalString (cudaAtLeast "12.8") ''
-    substituteInPlace ./makefiles/common.mk \
-      --replace-fail "-std=c++11" "-std=c++14"
+    patchShebangs ./src/device/symmetric/generate.py
   '';
 
   makeFlags = [