devel/qbs: update to 1.20, latest upstream, and changed ports norms
- Bump version and fix build.
- See CHANGES, 20200115: ${PREFIX}/share/man is for manpages, so remove the patch that put the manpages elsewhere, and update plist.
- When looking for qmake, look for suffixed names as well; we stopped using qtchooser some time ago, and adopted a qmake-qt5. Linux hosts do this with a check, we'll just true it in.
- Pull in an upstream patch to warn when there is no qmake; massage it to look for suffixed qmakes as well.
PR: 258444
Reported by: yuri