Retouch ccp executor example cmake to enable or not multi device building

[WilliamTambellini]

As of today
https://github.com/NVIDIA/TensorRT-LLM/blob/255779a91d6d3d137a792c3dd590a8284267bd35/examples/cpp/executor/CMakeLists.txt
hardcodes
-DENABLE_MULTI_DEVICE=1

TensorRT-LLM/examples/cpp/executor/CMakeLists.txt

Line 51 in 255779a

set(CMAKE_CXX_FLAGS "-Wall -pthread -lstdc++ -DENABLE_MULTI_DEVICE=1")

and then tries to build multi device.

This is just a proposal for ENABLE_MULTI_DEVICE to be overridable by cmake: eg:

if (not ${ENABLE_MULTI_DEVICE})
  set(ENABLE_MULTI_DEVICE 1)
endif()

set(CMAKE_CXX_FLAGS "-Wall -pthread -lstdc++ -DENABLE_MULTI_DEVICE=${ENABLE_MULTI_DEVICE}")
...

@tongyuantongyu ?

[brb-nv]

@tongyuantongyu do you think you can help with this?

[tongyuantongyu]

Thanks for the suggestion. @WilliamTambellini Would you like to create a PR for this?

[WilliamTambellini]

Sure, on it.