title: Qt linker errors: cannot find -lQtCored
body: <p>A problem with a Qt *.pro file:</p>
  
  <pre><code>TARGET = ProgName
  TEMPLATE = app
  CONFIG += console
  QT += core
  QT += gui
  
  LIBS += -LC:\\Qt\\4.8.5\\bin
  LIBS += -LC:\\Qt\\4.8.5\\lib
  LIBS += -LS:\\lib
  # LIBS += -lQtCored4         # not necessary
  # LIBS += -lQtCore4
  # LIBS += -lQtGuid4
  # LIBS += -lQtGui4
  
  SOURCES += ...
  HEADERS += ...
  </code></pre>
  
  <p>I get these linker errors:</p>
  
  <pre><code>:-1: error: cannot find -lQtGuid
  :-1: error: cannot find -lQtCored
  collect2.exe:-1: error: error: ld returned 1 exit status
  </code></pre>
  
  <p>All the DLLs exist in the specified directories.<br>
  The documentation did not help much.</p>
  
  <p>This pro file worked a few days ago, and it seems to have issues since I installed Qt 5.1 (this is not used, yet; I am still working with Qt4). </p>
  
  <p>Platform: Windows 7, MinGW, Qt 4.8.4</p>