cindex: fix test when missing time(1) executable

cindex: fix test when missing time(1) executable

It was only there for development purposes because associate is
slow, but it causes the test to get stuck on systems where it's
not available.  So remove it and just call join(1posix).

Note: this is not the `time' builtin found in shells, this
executable shows memory and pagefault info (and more with the
`-v' switch).  Unfortunately, it's not installed on many systems
despite being widely-packaged.

Reported-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>