Rip out the complete "reachable" checks, without replacement.

Rip out the complete "reachable" checks, without replacement.
It's a pity i spent time during t2k13 writing this; however,
when an entire concept is busted, let us not look back.

There is no such thing as an unreachable page.  Even if you are crazy
enough to put a page starting with ".Dt NAMEI 9" into a file man1/cat.1,
we now make sure that it can be found by all of the following:
Nm=namei Nm=cat sec=1 sec=9
It will always be displayed as:
cat(1) - pathname lookup
So you know that you have to type `man cat` to get at it.
That obsoletes the concept of "unreachable manuals" for good.