Diagnostic Message: Add required environment variable list in json which enforces their existent into the shell environment

{
    "project_name" : "SKVMOIP",
    "canonical_name" : "skvmoip",
    "description" : "Scalable KVM Over IP",
    "dependencies" : [ "common", "playvk", "bufferlib" ],
    "pre_config_hook" : "install_vulkan-headers.sh",
    "required_env_vars" : [ "CUDA_PATH", "VK_SDK_PATH" ],
    "vars" :
    {
        "cuda_path" : "run_command(find_program('python'), '-c', 'import os; print(os.environ[\"CUDA_PATH\"])', check : false).stdout().strip()",
        "cuda_includes" : "cuda_path + '/include'",
        "cuda_libs_path" : "cuda_path + '/lib/x64'",
        "vulkan_sdk_path" : "run_command(find_program('python'), '-c', 'import os; print(os.environ[\"VK_SDK_PATH\"])', check : false).stdout().strip()",
        "vulkan_libs_path" : "vulkan_sdk_path + '/Lib/'",
        "gtk3_cflags" : "run_command('pkg-config', 'gtk+-3.0', '--cflags', check : false).stdout().strip().split(' ')",
        "gtk3_libs" : "run_command('pkg-config', 'gtk+-3.0', '--libs', check : false).stdout().strip().split(' ')",
        "gui_sources" : [
            "source/GUI/AddUI.cpp",
            "source/GUI/MachineUI.cpp",
            "source/GUI/MainUI.cpp"
        ],
        "server_sources" : [
            "source/Encoder.cpp",
            "source/HDMIEncodeNetStream.cpp",
            "source/Win32/Win32ImagingDevice.cpp"
        ],
        "client_sources" : [
            "source/third_party/NvDecoder.cpp",
            "source/Decoder.cpp",
            "source/Window.cpp",
            "source/Win32/Win32DrawSurface.cpp",
            "source/Win32/Win32RawInput.cpp",
            "source/Win32/Win32Window.cpp",
            "source/HDMIDecoderNetStream.cpp",
            "source/KMNetStream.cpp",
            "source/HIDUsageID.cpp",
            "source/RDPSession.cpp",
            "source/PresentEngine.cpp",
            "source/MachineData.cpp",
            "source/FIFOPool.cpp",
            "source/Event.cpp",
            "source/Network/NetworkPacket.cpp",
            "source/ErrorHandling.cpp"
        ]
    },
    "defines" : [ 
        "-DUSE_PERSISTENT_SETTINGS",
        "-DUSE_VULKAN_PRESENTATION",
        "-DUSE_VULKAN_FOR_COLOR_SPACE_CONVERSION",
        "-DUSE_DIRECT_FRAME_DATA_COPY"
    ],
    "release_defines": [ "-DSKVMOIP_RELEASE" ],
    "debug_defines": [ "-DSKVMOIP_DEBUG" ],
    "install_header_dirs" : [ "include/SKVMOIP" ],
    "include_dirs" : [ "include", "external-dependencies" ],
    "windows_link_args" : [
        "-lws2_32",
        "-lole32",
        "-loleaut32",
        "-lmfreadwrite",
        "-lmfplat",
        "-lmf",
        "-lmfuuid",
        "-lgdi32",
        "-lwmcodecdspuuid"
    ],
    "targets" :
    [
        {
            "name" : "server",
            "is_executable" : true,
            "windows_link_args" : [
                "link_dir: './external-dependencies/x264'", "-lx264"
            ],
            "defines" : ["-DBUILD_SERVER"],
            "sources": [ "$server_sources", "source/main.server.cpp" ]
        },
        {
            "name" : "client",
            "is_executable" : true,
            "dependencies" : ["gtk+-3.0", "vulkanheaders"],
            "include_dirs" : [
                "./external-dependencies/NvidiaCodec/include/",
                "$cuda_includes"
            ],
            "windows_link_args" : [
                "link_dir: $cuda_libs_path", "-l:cuda.lib",
                "link_dir: './external-dependencies/NvidiaCodec/'", "-l:nvcuvid.lib",
                "link_dir: $vulkan_libs_path", "-lvulkan-1"                
            ],
            "defines" : ["-DBUILD_CLIENT"],
            "sources" : [ "$client_sources", "$gui_sources", "source/main.client.cpp" ],
            "required_env_var" : [ "CUDA_PATH", "VK_SDK_PATH" ]
        }
    ],
    "sources" : [
        "source/Network/NetworkSocket.cpp",
        "source/Network/NetworkAsyncQueueSocket.cpp",
        "source/VideoSourceStream.cpp",
        "source/Win32/Win32.cpp"
    ]
}