For me the issue was that I was launching mumble via a .desktop that pointed to a sym link I placed in /usr/bin pointing to ~/mumble/release/mumble.
If I launched mumble manually through it's release directory, I didn't get this warning.
To fix this I added `CONFIG+=no-bundled-celt` to the qmake line and installed libcelt packages and it's working now.
For me the issue was that I was launching mumble via a .desktop that pointed to a sym link I placed in /usr/bin pointing to ~/mumble/ release/ mumble.
If I launched mumble manually through it's release directory, I didn't get this warning.
To fix this I added `CONFIG+ =no-bundled- celt` to the qmake line and installed libcelt packages and it's working now.