Sigh. Looks like this was a pebkac error.
The one-liner problem was real. Commenting out that patch allowed amarok to compile completely.
The segfault problem was me.
I have two 13.1 systems installed on my hard drives. One contains the build system and the other is where I methodically install and test the new packages. The 13.1 system with the chroot build environment uses the KDE 3.5.10 packages from 12.2. The chroot environment contains KDE packages built for 13.1. I was trying to run the new amarok package in the non-chroot environment. That is, I was trying to run the new amarok package in the wrong KDE environment. Hence, no wonder I saw the segfault error.
The new amarok package works just fine in the testing environment.
I'm posting this message from 13.1 with all the newly built KDE packages.
Not a total waste of time. I learned a wee bit about using gdb.
I'm still seeing these errors:
libpng warning: Application was compiled with png.h from libpng-1.4.3
libpng warning: Application is running with png.c from libpng-1.2.44
libpng error: Incompatible libpng version in application and library
I don't see the KWikDisk icon in the system tray. Likely related to the libpng errors.
Some housecleaning and reinstalling a few packages seems to have solved the libpng error messages.