I got this solved.  Turned out to be the simplest of things, in retrospect.  Andras had it right as to being a 64 v. 32 bit issue.  On trying to compile KMyMoney, I ran into the exact same error, which led me on a succession of trial, error, and Googling (introducing me, along the way, to the wonderful world of multiarch issues), leading to, for the record:

./configure --libdir=/usr/lib64

This being the first x86_64 system I've had, this simply had never entered my head.

But all is fine now.  There were no problems at all, unsurprisingly, with make and make install.  A quick download and compile of Tidy as suggested when I first ran Quanta, and I'm on my way.  The input from both of you helped me on the right path; thanks again!

Terrific software, by the way. 

Chris