adding natively portable binaries (all statically linked with libc++, without nixpkgs help) for x86-64 linux

.github/workflows/build-ton-linux-x86-64-portable.yml

@@ -0,0 +1,36 @@
+name: Ubuntu TON build (portable, x86-64)
+
+on: [push,workflow_dispatch,workflow_call]
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-20.04, ubuntu-22.04, ubuntu-24.04]
+    runs-on: ${{ matrix.os }}
+
+    steps:
+    - name: Check out repository
+      uses: actions/checkout@v3
+      with:      
+        submodules: 'recursive'
+
+    - name: Install system libraries
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y build-essential git cmake ninja-build libc++-dev libc++abi-dev
+
+    - name: Build TON
+      run: |
+        git submodule sync --recursive
+        git submodule update
+        cp assembly/native/build-ubuntu-portable.sh .
+        chmod +x build-ubuntu-portable.sh
+        ./build-ubuntu-portable.sh -t -a
+
+    - name: Upload artifacts
+      uses: actions/upload-artifact@master
+      with:
+        name: ton-binaries-${{ matrix.os }}
+        path: artifacts

assembly/native/build-ubuntu-portable.sh

@@ -1,7 +1,7 @@
 #/bin/bash
 
 #sudo apt-get update
-#sudo apt-get install -y build-essential git cmake ninja-build automake libtool texinfo autoconf
+#sudo apt-get install -y build-essential git cmake ninja-build automake libtool texinfo autoconf libc++-dev libc++abi-dev
 
 with_tests=false
 with_artifacts=false
@@ -24,8 +24,8 @@ else
   rm -rf .ninja* CMakeCache.txt
 fi
 
-export CC=$(which clang-16)
-export CXX=$(which clang++-16)
+export CC=$(which clang)
+export CXX=$(which clang++)
 export CCACHE_DISABLE=1
 
 if [ ! -d "lz4" ]; then
@@ -101,6 +101,8 @@ else
 fi
 
 cmake -GNinja .. \
+-DCMAKE_CXX_FLAGS="-stdlib=libc++" \
+-DCMAKE_EXE_LINKER_FLAGS="-stdlib=libc++" \
 -DPORTABLE=1 \
 -DCMAKE_BUILD_TYPE=Release \
 -DOPENSSL_FOUND=1 \