Fixes 'static assertion failed: static_assert(sizeof(CCameraAngles) == 0x408, "");'
when compiling pkgsi686Linux.mumble, which is a dependency of x64 mumble_overlay.
As it stands, the mumble-overlay install phase attemps to link
`{mumble}/lib/libmumble.so.1.2.*` to its output's `lib/libmumble.so.1`,
this has stopped matching any file ever since mumble has passed
version 1.3.
Instead, we simply link from `{mumble}/lib/libmumble.so.1`
