ffmpeg: fix nvcc build

pkgs/development/libraries/ffmpeg/generic.nix

@@ -436,6 +436,9 @@ stdenv.mkDerivation (
           hash = "sha256-l1t4LcUDSW757diNu69NzvjenW5Mxb5aYtXz64Yl9gs=";
         })
       ]
+      ++ optionals (lib.versionAtLeast version "5.1") [
+        ./nvccflags-cpp14.patch
+      ]
       ++ optionals (lib.versionAtLeast version "6.1" && lib.versionOlder version "6.2") [
         (fetchpatch2 {
           # this can be removed post 6.1

pkgs/development/libraries/ffmpeg/nvccflags-cpp14.patch

@@ -0,0 +1,13 @@
+diff --git a/configure b/configure
+index ffa407d53d..f3e223cfac 100755
+--- a/configure
++++ b/configure
+@@ -6742,7 +6742,7 @@ if [ -z "$nvccflags" ]; then
+     nvccflags=$nvccflags_default
+ fi
+
+-nvccflags="$nvccflags -std=c++11"
++nvccflags="$nvccflags -std=c++14"
+
+ if enabled x86_64 || enabled ppc64 || enabled aarch64; then
+     nvccflags="$nvccflags -m64"