gcc12: disable libsanitizer for mips64

    Without the change build on mips64-unknown-linux-gnu fails as:

        $ nix-build -A buildPackages.gcc12 --argstr crossSystem mips64-linux

        In file included from ...-glibc-mips64-unknown-linux-gnu-2.37-8-dev/include/bits/stat.h:25,
                         from ...-glibc-mips64-unknown-linux-gnu-2.37-8-dev/include/fcntl.h:78,
                         from ../../../../gcc-12.3.0/libsanitizer/sanitizer_common/sanitizer_linux.cpp:55:
        ...-glibc-mips64-unknown-linux-gnu-2.37-8-dev/include/bits/struct_stat.h:190:8: error: redefinition of 'struct stat64'
          190 | struct stat64
              |        ^~~~~~

pkgs/development/compilers/gcc/12/default.nix

@@ -288,7 +288,10 @@ lib.pipe (stdenv.mkDerivation ({
 
   configurePlatforms = [ "build" "host" "target" ];
 
-  configureFlags = callFile ../common/configure-flags.nix { };
+  configureFlags = callFile ../common/configure-flags.nix { }
+    # On mips64-unknown-linux-gnu libsanitizer defines collide with
+    # glibc's definitions and fail the build. It was fixed in gcc-13+.
+    ++ lib.optionals targetPlatform.isMips [ "--disable-libsanitizer" ];
 
   targetConfig = if targetPlatform != hostPlatform then targetPlatform.config else null;