The UTF-8 quotes can appear in man pages etc as well, not only C code.
For example, in xcb_composite_redirect_subwindows.3:

    xcb_composite_redirect_subwindows - Redirect all current and future
    children of ‘window’

Note that window is quoted by a pair of UTF-8 single quotes.

Closes: #72
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Part-of: <!60>