configure script doesn't check for `make` ahead of time

[pnkfelix]

This is admittedly silly.

But I was setting up a new machine, and running the rust configure on it, it checks for most of the program it needs at the outset, but for GNU make, it just assumes that it is already there and blithely goes ahead and attempts to configure e.g. LLVM.

Its not hard for an end user to respond to, but it would be slightly cleaner if we checked for make at the same time in configure where we check for everything else.

[pnkfelix]

part of #8058