[lldb] Increase LINK_INTERFACE_MULTIPLICITY for Debug builds

On Fedora 30 x86_64 with
	cmake ../llvm-monorepo/llvm/ -DCMAKE_BUILD_TYPE=Debug  -DLLVM_USE_LINKER=gold -DLLVM_ENABLE_PROJECTS="lldb;clang;lld"  -DLLVM_USE_SPLIT_DWARF=ON -DCMAKE_C_COMPILER=clang  -DCMAKE_CXX_COMPILER=clang++ -DLLVM_ENABLE_ASSERTIONS=ON

It does not affect Release builds.

getting:
	lldb/source/Expression/IRInterpreter.cpp:1471: error: undefined reference to 'lldb_private::ThreadPlanCallFunctionUsingABI::ThreadPlanCallFunctionUsingABI(lldb_private::Thread&, lldb_private::Address const&, llvm::Type&, llvm::Type&, llvm::ArrayRef<lldb_private::ABI::CallArgument>, lldb_private::EvaluateExpressionOptions const&)'
	lldb/source/Expression/LLVMUserExpression.cpp:148: error: undefined reference to 'lldb_private::ThreadPlanCallUserExpression::ThreadPlanCallUserExpression(lldb_private::Thread&, lldb_private::Address&, llvm::ArrayRef<unsigned long>, lldb_private::EvaluateExpressionOptions const&, std::shared_ptr<lldb_private::UserExpression>&)'

Pavel Labath has suggest LINK_INTERFACE_MULTIPLICITY could be further
increased.

Differential Revision: https://reviews.llvm.org/D73847