Add necessary runtimes

Author: joshherr-quic

docker/install/ubuntu_install_hexagon.sh

@@ -38,6 +38,7 @@ cmake \
   -DLLVM_ENABLE_ASSERTIONS=ON \
   -DLLVM_TARGETS_TO_BUILD:STRING="Hexagon;X86" \
   -DLLVM_ENABLE_PROJECTS:STRING="clang;llvm" \
+  -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi" \
   -DTARGET_TRIPLE=x86_64-unknown-linux-gnu \
   -DLLVM_DEFAULT_TARGET_TRIPLE=x86_64-unknown-linux-gnu \
   ../llvm
@@ -46,3 +47,7 @@ ninja install
 popd
 popd
 rm -rf llvm-hexagon
+
+# Add runtimes to sytem library path
+echo "/opt/clang-llvm/lib/x86_64-unknown-linux-gnu" > /etc/ld.so.conf.d/libcxx.conf
+ldconfig