test: concatenate string literals outside array

src/video_output/video_output.c:302:44: warning: suspicious concatenation of string literals in an array initialization; did you mean to separate the elements with a comma? [-Wstring-concatenation]
        "--no-auto-preparse", "--dec-dev=" MODULE_STRING,
                                           ^
                                          ,
modules/stream_out/transcode.c:370:44: warning: suspicious concatenation of string literals in an array initialization; did you mean to separate the elements with a comma? [-Wstring-concatenation]
        "--no-auto-preparse", "--dec-dev=" MODULE_STRING,
                                           ^
                                          ,