Hi

Hi, 

when run k3b frameworks branch (kf5/Qt5), the plugin k3bmaddecoder don't load.

libmad is installed, and detected by cmake: http://sl1pkn07.wtf/paste/view/c371aee6
k3bmaddecoder is builded and installed correctly in the other plugin place

uses libmad 0.15.1b

Reproducible: Always

Steps to Reproduce:
1. donload k3b from kf5 branch and install libmad (and other dependencies
2. build and install
3. run k3b and see the configuration window error

Actual Results:  
k3b don't load the libmad plugin

Expected Results:  
k3b can load the libmad plugin

(K3b::Core) System problems:
 WARNING
 PROBLEM:   "MP3 Audio Decoder plugin not found." 
 DETAILS:   "K3b could not load or find the MP3 decoder plugin. This means that you will not be able to create Audio CDs from MP3 files. Many Linux distributions do not include MP3 support for legal reasons." 
 SOLUTION:  "To enable MP3 support, please install the MAD MP3 decoding library as well as the K3b MAD MP3 decoder plugin (the latter may already be installed but not functional due to the missing libmad). Some distributions allow installation of MP3 support via an online update tool."

this message is repeat some times, and spawn a warning window in k3b with the same message