mkhelp: generate code for --disable-manual as well
This allows configure --disable-manual to run and build without having
to regenerate the src/tool_hugehelp.c file which otherwise is necessary
since we ship tarballs with that file present.
(From OE-Core rev: 544a96255203a6779d1f0022d003c6680f330511)
(From OE-Core rev: 4176809145037aed3d009c3ab96ef9ace519ca46)
Signed-off-by: Tudor Florea <tudor.florea@enea.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>