ci: use rpath-link and rpath so partition-alloc can find our libc++

rpath-link is needed for the link step, rpath is needed for runtime

this may conflict with what CMake wants to do with rpaths, but seems to work for now

.github/workflows/ci.yml

@@ -173,14 +173,12 @@ jobs:
           Clang_DIR=`realpath $LLVM_DIR/../clang`
           mkdir build
           pushd build
-          cross_link_flags="-B$(pwd)/../llvm-project/build-rtlibs/compiler-rt/lib/linux \
-          -L`pwd`/../llvm-project/build-rtlibs/lib \
+          rtlibs_dir="$(pwd)/../llvm-project/build-rtlibs"
+          cross_link_flags="-B${rtlibs_dir}/compiler-rt/lib/linux -L${rtlibs_dir}/lib \
           --rtlib=compiler-rt --unwindlib=libunwind"
-          # TODO: rpath needs addition but this would override it:
-          # "-Wl,-rpath,$(pwd)/../llvm-project/build-rtlibs/lib"
           cross_flags="-isystem /usr/aarch64-linux-gnu/include --gcc-toolchain=/usr \
           -march=armv8.5-a+memtag -ffixed-x18 --rtlib=compiler-rt --stdlib=libc++ \
-          -I$(pwd)/../llvm-project/build-rtlibs/include/c++/v1"
+          -I${rtlibs_dir}/include/c++/v1"
           export LDFLAGS="-L/usr/aarch64-linux-gnu/lib"
           cmake .. \
             -DCMAKE_CROSSCOMPILING_EMULATOR=${{ github.workspace }}/qemu/build/qemu-aarch64 \
@@ -190,8 +188,8 @@ jobs:
             -DCMAKE_OBJCOPY=/usr/bin/llvm-objcopy-15 \
             -DCMAKE_C_FLAGS="$cross_flags" \
             -DCMAKE_CXX_FLAGS="$cross_flags" \
-            -DCMAKE_EXE_LINKER_FLAGS="$cross_link_flags -lm" \
-            -DCMAKE_SHARED_LINKER_FLAGS="$cross_link_flags" \
+            -DCMAKE_EXE_LINKER_FLAGS="$cross_link_flags -lm -Wl,-rpath-link,${rtlibs_dir}/lib" \
+            -DCMAKE_SHARED_LINKER_FLAGS="$cross_link_flags -Wl,-rpath,${rtlibs_dir}/lib" \
             -DClang_DIR=$Clang_DIR                                  \
             -DCLANG_EXE=`which clang-15`                            \
             -DLLVM_DIR=$LLVM_DIR                                    \