Add cuda compilation environment support

[waruqi]

Support CUDA Toolkit http://docs.nvidia.com/cuda/index.html

• linux
• macosx
• windows Please download 2.10.0-dev pacakge

[waruqi]

xmake will detect cuda sdk environment automatically, we can only run the following command to compile cuda program:

$ xmake

And we can also configure a given cuda sdk directory if detect failed.

$ xmake f --cuda=/usr/local/cuda-9.1/ 
$ xmake

[waruqi]

Create an empty project for cuda:

$ xmake create -P test -l cuda
$ cd test
$ xmake

[waruqi]

[waruqi]

-- define target
target("cuda_console")

    -- set kind
    set_kind("binary")

    -- add include directories
    add_includedirs("inc")

    -- add files
    add_files("src/*.cu")

    -- generate SASS code for each SM architecture
    for _, sm in ipairs({"30", "35", "37", "50", "52", "60", "61", "70"}) do
        add_cuflags("-gencode arch=compute_" .. sm .. ",code=sm_" .. sm)
        add_ldflags("-gencode arch=compute_" .. sm .. ",code=sm_" .. sm)
    end

    -- generate PTX code from the highest SM architecture to guarantee forward-compatibility
    sm = "70"
    add_cuflags("-gencode arch=compute_" .. sm .. ",code=compute_" .. sm)
    add_ldflags("-gencode arch=compute_" .. sm .. ",code=compute_" .. sm)