updates LMMS to 1.2.0-rc7
- Add sndio support
- Get rid of many custom patches and other workarounds by adding USES=localbase:ldflags
- Fix man page install location
- Modernize some CMAKE variables
Changelog: https://github.com/LMMS/lmms/releases/tag/v1.2.0-rc7
PR: 229867
Submitted by: tobik