all-packages/test: add gcc9Stdenv, cc-wrapper-gcc9

Follow up from #60860.

Signed-off-by: Austin Seipp <aseipp@pobox.com>

pkgs/test/default.nix

@@ -7,6 +7,7 @@ with pkgs;
   cc-wrapper-gcc = callPackage ./cc-wrapper { stdenv = gccStdenv; };
   cc-wrapper-gcc7 = callPackage ./cc-wrapper { stdenv = gcc7Stdenv; };
   cc-wrapper-gcc8 = callPackage ./cc-wrapper { stdenv = gcc8Stdenv; };
+  cc-wrapper-gcc9 = callPackage ./cc-wrapper { stdenv = gcc9Stdenv; };
   cc-wrapper-clang = callPackage ./cc-wrapper { stdenv = llvmPackages.stdenv; };
   cc-wrapper-libcxx = callPackage ./cc-wrapper { stdenv = llvmPackages.libcxxStdenv; };
   cc-wrapper-clang-39 = callPackage ./cc-wrapper { stdenv = llvmPackages_39.stdenv; };

pkgs/top-level/all-packages.nix

@@ -7088,6 +7088,7 @@ in
 
   gcc7Stdenv = overrideCC gccStdenv gcc7;
   gcc8Stdenv = overrideCC gccStdenv gcc8;
+  gcc9Stdenv = overrideCC gccStdenv gcc9;
 
   wrapCCMulti = cc:
     if stdenv.targetPlatform.system == "x86_64-linux" then let