gen-input.sh generates a header file in which C++ keywords are used as C identifiers.
gen-expected-tags.sh generates an incomplete expected.tags.

Copyed from #930:

    I found this case in linux kernel.

    Consider a C language header having .h suffix.
    In C language private is not a keyword.
    New Cxx parser doesn't record a variable named private because
    the parser recognized it as C++ keyword.``
    Old Cxx parser

    [yamato@x201]/tmp% cat foo.h
    extern int private;
    static inline int f(void)
    {
      return private;
    }
    typedef int int32;


    [yamato@x201]/tmp% u-ctags -o - /tmp/foo.h 
    # nothing is captured.

    [yamato@x201]/tmp% u-ctags --languages=+OldC++ --language-force=OldC++ -o - /tmp/foo.h
    f   /tmp/foo.h  /^static inline int f(void)$/;" f
    int32   /tmp/foo.h  /^typedef int int32;$/;"    t
