Make cr_bsd_visible()'s sub-functions internal

[olce]

Summary

cr_canseeotheruids(), cr_canseeothergids() and cr_canseejailproc() should not be
used directly now. cr_bsd_visible() has to be called instead.

[zlei]

These functions are exported, I think they should be kept as is to keep KPI compatibility.

[olce]

We can change KPI across major versions at least, can't we?

This change has several goals. The first is to prevent consumers from using any of these individual functions, which are called by cr_bsd_visibility() itself. This helps avoid bugs where some callers forget to check if a particular policy authorizes accesses, which is exactly what happened with see_jail_proc. A second goal is that, more conceptually, visibility policies can be seen as a block that should be applied at once. If, in the future, some policy is added, it will just have to in cr_bsd_visibility() (no need of sprinkling calls all around).

[olce]

Rename cr_bsd_visibility() to cr_bsd_visible().

[olce]

Update context lines after update of D40626.

[olce]

Update context lines.

[olce]

Re-validate, since no actual changes.