gcc: use sanitiseHeaderPathsHook

This reduces the WebKitGTK runtime closure size from 1.45 GiB to
1.22 GiB on `aarch64-linux`, as measured by `nix-tree`.

pkgs/development/compilers/gcc/common/dependencies.nix

@@ -12,6 +12,7 @@
   gmp,
   mpfr,
   libmpc,
+  sanitiseHeaderPathsHook,
   libucontext ? null,
   libxcrypt ? null,
   isSnapshot ? false,
@@ -42,6 +43,10 @@ in
       texinfo
       which
       gettext
+
+      # Prevent GCC leaking into the runtime closure of C++ packages
+      # through headers using `__FILE__`.
+      sanitiseHeaderPathsHook
     ]
     ++ optionals (perl != null) [ perl ]
     ++ optionals (with stdenv.targetPlatform; isVc4 || isRedox || isSnapshot && flex != null) [ flex ]

pkgs/development/compilers/gcc/default.nix

@@ -49,6 +49,7 @@
     !enablePlugin
     || (stdenv.targetPlatform.isAvr && stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isAarch64),
   nukeReferences,
+  sanitiseHeaderPathsHook,
   callPackage,
   majorMinorVersion,
   apple-sdk,
@@ -179,6 +180,7 @@ let
       pkgsBuildTarget
       profiledCompiler
       reproducibleBuild
+      sanitiseHeaderPathsHook
       staticCompiler
       stdenv
       targetPackages