avoid using auto-generated variable names

theories/lang/lib/arc.v

theories/lang/lib/new_delete.v

theories/lang/lifting.v

theories/typing/borrow.v

theories/typing/examples/nonlexical.v

theories/typing/lib/arc.v

theories/typing/lib/diverging_static.v

theories/typing/lib/mutex/mutex.v

theories/typing/lib/panic.v

theories/typing/lib/rc/rc.v

theories/typing/lib/refcell/refcell.v

theories/typing/lib/rwlock/rwlock.v

theories/typing/lib/rwlock/rwlock_code.v

theories/typing/lib/spawn.v

theories/typing/own.v

theories/typing/product_split.v

theories/typing/type.v

theories/typing/type_context.v

theories/typing/type_sum.v

theories/typing/uninit.v