Hello,
Yes theres no great way to add custom linker arg, the only way would be to change this file:
Engine/Source/Programs/UnrealBuildTool/Platform/Linux/LinuxToolChain.cs
And in this function:
protected virtual string GetLinkArguments(LinkEnvironment LinkEnvironment)
Add this somewhere along with the other linker flags:
results += " -Wl,--copy-dt-needed-entries";