Auto merge of rust-lang#103150 - joboet:remove_lock_wrappers, r=m-ou-se

Remove lock wrappers in `sys_common`

This moves the lazy allocation to `sys` (SGX and UNIX). While this leads to a bit more verbosity, it will simplify future improvements by making room in `sys_common` for platform-independent implementations.

This also removes the condvar check on SGX as it is not necessary for soundness and will be removed anyway once mutex has been made movable.

For simplicity's sake, `libunwind` also uses lazy allocation now on SGX. This will require an update to the C definitions before merging this (CC `@raoulstrackx).`

r? `@m-ou-se`