gccWithoutTargetLibc: enable langCC

Previously gccWithoutTargetLibc was built with `langCC = false;`, which
meant stdenvNoLibc had C++ support when not cross compiling or when the
host platform toolchain is LLVM, but did not have C++ support when cross
compiling for a non-Darwin and non-LLVM host platform. This patch fixes
issues when cross compiling C++ packages built with stdenvNoLibc like
LLVM libc and the mlibc package I'm (sanana) working on.

Co-Authored-By: Artturin <Artturin@artturin.com>
Co-Authored-By: Arsen Arsenović <arsen@aarsen.me>

pkgs/development/compilers/gcc/common/configure-flags.nix

@@ -68,6 +68,11 @@ let
       "--disable-libatomic" # requires libc
       "--disable-decimal-float" # requires libc
       "--disable-libmpx" # requires libc
+      "--disable-hosted-libstdcxx"
+      "--disable-libstdcxx-backtrace"
+      "--disable-linux-futex"
+      "--disable-libvtv"
+      "--disable-libitm"
     ] ++ lib.optionals crossMingw [
       "--with-headers=${lib.getDev libcCross}/include"
       "--with-gcc"

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

@@ -8,6 +8,7 @@
   which,
   gettext,
   gnused,
+  autoconf269,
   patchelf,
   gmp,
   mpfr,
@@ -49,7 +50,8 @@ in
     ++ optionals langRust [ cargo ]
     # The builder relies on GNU sed (for instance, Darwin's `sed' fails with
     # "-i may not be used with stdin"), and `stdenvNative' doesn't provide it.
-    ++ optionals buildPlatform.isDarwin [ gnused ];
+    ++ optionals buildPlatform.isDarwin [ gnused ]
+    ++ optionals withoutTargetLibc [ autoconf269 ];
 
   # For building runtime libs
   # same for all gcc's

pkgs/development/compilers/gcc/common/pre-configure.nix

@@ -48,6 +48,16 @@ lib.optionalString (hostPlatform.isSunOS && hostPlatform.is64bit) ''
   export STRIP='strip -x'
 ''
 
+
++ lib.optionalString withoutTargetLibc ''
+  for i in */configure.ac; do
+    pushd "$(dirname "$i")"
+    echo "Running autoreconf in $PWD"
+    autoconf -f
+    popd
+  done
+''
+
 # HACK: if host and target config are the same, but the platforms are
 # actually different we need to convince the configure script that it
 # is in fact building a cross compiler although it doesn't believe it.

pkgs/development/compilers/gcc/default.nix

@@ -16,6 +16,7 @@
 , texinfo ? null
 , perl ? null # optional, for texi2pod (then pod2man)
 , gmp, mpfr, libmpc, gettext, which, patchelf, binutils
+, autoconf269
 , isl ? null # optional, for the Graphite optimization framework.
 , zlib ? null
 , libucontext ? null
@@ -103,6 +104,7 @@ let
       # inherit generated with 'nix eval --json --impure --expr "with import ./. {}; lib.attrNames (lib.functionArgs gcc${majorVersion}.cc.override)" | jq '.[]' --raw-output'
       inherit
         apple-sdk
+        autoconf269
         binutils
         buildPackages
         cargo

pkgs/top-level/all-packages.nix

@@ -6040,7 +6040,6 @@ with pkgs;
         isl = if !stdenv.hostPlatform.isDarwin then isl_0_20 else null;
 
         withoutTargetLibc = true;
-        langCC = false;
         libcCross = libcCross1;
         targetPackages.stdenv.cc.bintools = binutilsNoLibc;
         enableShared =