cmake vcpkg elfutil libdw missing '<dlfcn.h>'

[yhyu13]

Hi,

My system:
Ubuntu 20.04, clang16, cmake3.28,

I am on latest commit 51f0700 as for now Feb 2024

I used vckpkg to install elfutil using vkpkg.json, I intended to use libdw with backwardcpp

{
    "dependencies": [  
        "spdlog",
        "mimalloc",
        "magic-enum",
        "boost",
        "elfutils"
    ],
    "builtin-baseline": "53bef8994c541b6561884a8395ea35715ece75db"
}

And used fetch content to install backwardcpp

FetchContent_Declare(
    backward
    GIT_REPOSITORY https://github.com/yhyu13/backward-cpp
    GIT_TAG 51f0700452cf71c57d43c2d028277b24cde32502  # or a version tag, such as v1.6
    GIT_SHALLOW 1 # optional ( --depth=1 )
    GIT_PROGRESS TRUE
    SYSTEM          # optional, the Backward include directory will be treated as system directory
)
FetchContent_MakeAvailable(backward)
# Add Backward to your target (either Backward::Interface, Backward::Object, or Backward::Backward)
target_link_libraries(Common PUBLIC Backward::Interface)

Then in my test case TestException.cpp, I included #include <backward.hpp>

The the compile target fails with dlopen cannot find under libdw source code, bascially it is the file '<dlfcn.h>' (libld) that is missing from linker.

/usr/bin/ld: vcpkg_installed/x64-linux/debug/lib/libdw.a(debuginfod-client.o): in function `__libdwfl_debuginfod_init':
/home/hangyu5/Documents/Gitrepo-My/HLVM-Engine/Engine/Source/Dependency/vcpkg/buildtrees/elfutils/x64-linux-dbg/libdwfl/.././../src/14cf90c2be-0bcffe8e4e.clean/libdwfl/debuginfod-client.c:104: undefined reference to `dlopen'
/usr/bin/ld: /home/hangyu5/Documents/Gitrepo-My/HLVM-Engine/Engine/Source/Dependency/vcpkg/buildtrees/elfutils/x64-linux-dbg/libdwfl/.././../src/14cf90c2be-0bcffe8e4e.clean/libdwfl/debuginfod-client.c:108: undefined reference to `dlsym'
/usr/bin/ld: /home/hangyu5/Documents/Gitrepo-My/HLVM-Engine/Engine/Source/Dependency/vcpkg/buildtrees/elfutils/x64-linux-dbg/libdwfl/.././../src/14cf90c2be-0bcffe8e4e.clean/libdwfl/debuginfod-client.c:109: undefined reference to `dlsym'
/usr/bin/ld: /home/hangyu5/Documents/Gitrepo-My/HLVM-Engine/Engine/Source/Dependency/vcpkg/buildtrees/elfutils/x64-linux-dbg/libdwfl/.././../src/14cf90c2be-0bcffe8e4e.clean/libdwfl/debuginfod-client.c:111: undefined reference to `dlsym'
/usr/bin/ld: /home/hangyu5/Documents/Gitrepo-My/HLVM-Engine/Engine/Source/Dependency/vcpkg/buildtrees/elfutils/x64-linux-dbg/libdwfl/.././../src/14cf90c2be-0bcffe8e4e.clean/libdwfl/debuginfod-client.c:113: undefined reference to `dlsym'
/usr/bin/ld: /home/hangyu5/Documents/Gitrepo-My/HLVM-Engine/Engine/Source/Dependency/vcpkg/buildtrees/elfutils/x64-linux-dbg/libdwfl/.././../src/14cf90c2be-0bcffe8e4e.clean/libdwfl/debuginfod-client.c:125: undefined reference to `dlclose'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

After googling a bit, I found this solution here https://gist.github.com/kwk/3595733

which simply added

target_link_libraries(Common PUBLIC ${CMAKE_DL_LIBS})

To my program target Common that backwardcpp linked to.

Consider add this to the README?