libserial: prevent documentation from being build
If docbook2pdf is present on the host, the documentation is built, no
matter all the --disable-doc*
But forcing ac_cv_prog_DOCBOOK2PDF to no tells configure that
docbook2pdf is absent, and thus the documentation is not built.
Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Richard Genoud