title: Q_IMPORT_PLUGIN compiling error with qgif and qjpeg plugin
body: <p>I have some problem when a try to build my code upon the 4.7.4 dynamic version.  I have linkage error because of the 2 following lines :</p>
  
  <p>Q_IMPORT_PLUGIN(qgif)
  Q_IMPORT_PLUGIN(qjpeg)</p>
  
  <p>To resolve the problem i just commented the above lines.  Now everything compile correctly, which is strange.  Does that mean that the code is not using the plugin (look a stupid question, but the project has several hundred thousand lines, i don,t know every part of it)</p>
  
  <p>Question : What is the purpose of qgif and qjped plugin.  Should i expect code using explicitly functions form these plugins?</p>
  
  <p>I just want to be sure that i will not broke something by committing these lines...</p>