title: qmake — loop doesn't split line
body: <p>This is works as expected (removes files):</p>
  
  <pre><code>defineTest(removeFiles) {
      FILES_TO_DEL = $$shell_path($$1) # full paths
      RETURN = $$escape_expand(\n\t)
      for(FILE, FILES_TO_DEL){
          QMAKE_POST_LINK += $$RETURN $$QMAKE_DEL_FILE $$quote($$FILE)
      }
      export(QMAKE_POST_LINK)
  }
  
  
  FILES_TO_DEL = $$DESTDIR/imageformats/qicns.dll \
                 $$DESTDIR/imageformats/qico.dll \
                 $$DESTDIR/imageformats/qtga.dll \
                 $$DESTDIR/imageformats/qtiff.dll \
                 $$DESTDIR/imageformats/qwbmp.dll \
                 $$DESTDIR/imageformats/qwebp.dll
  removeFiles($$FILES_TO_DEL)
  </code></pre>
  
  <p>But better way doesn't remove anything:</p>
  
  <pre><code>defineTest(removeFilesInDir) {
      PATH_TO_DEL = $$shell_path($$1)
      FILES_TO_DEL = $$shell_path($$2)
      message($$PATH_TO_DEL)
      message($$FILES_TO_DEL)
      RETURN = $$escape_expand(\n\t)
      for(FILE, FILES_TO_DEL){
          message($$FILE)
          QMAKE_POST_LINK += $$RETURN $$QMAKE_DEL_FILE $$quote($${PATH_TO_DEL}$${FILE})
      }
      export(QMAKE_POST_LINK)
  }
  
  
  FDIR = $$DESTDIR/imageformats/
  FFILES = qicns.dll qico.dll qtga.dll qtiff.dll qwbmp.dll qwebp.dll
  removeFilesInDir($${FDIR}, $${FFILES})
  </code></pre>
  
  <p><code>message($$PATH_TO_DEL)</code> shows correct path,<br>
  <code>message($$FILES_TO_DEL)</code> shows  <code>"qicns.dll qico.dll qtga.dll qtiff.dll qwbmp.dll qwebp.dll"</code> (as expected),<br>
  but <code>message($$FILE)</code> shows the same <code>"qicns.dll qico.dll qtga.dll qtiff.dll qwbmp.dll qwebp.dll"</code> (only ones).  </p>
  
  <p><strong>Why loop in <code>removeFilesInDir</code> doesn't split line the same way as in <code>removeFiles</code>? How to fix <code>removeFilesInDir</code> ?</strong></p>
  
  <hr>
  
  <p>Windows, Qt 5.9, QtCreator, qmake at .pro and .pri files. </p>