title: Could not load Spatialite extension in qSqlite ( QT 5.9)
body: <p>I am trying to load Spatialite as extension in qSqlite ( Qt 5.9), I have done that before with Qt4.8, but I failed with the QT5.9.
  I changed the sqlite.pri by removing "SQLITE_OMIT_LOAD_EXTENSION", and I did some change on the sqlite.c by removing the "<code>#define SQLITE_OMIT_LOAD_EXTENSION 1</code>", and adding "<code>#define SQLITE_ENABLE_LOAD_EXTENSION 1</code>".
  I also add the following lines to openDatabase(....)</p>
  
  <pre><code>#if defined(SQLITE_ENABLE_LOAD_EXTENSION)
  | SQLITE_LoadExtension|SQLITE_LoadExtFunc
  #endif
  </code></pre>
  
  <p>Now the "requet.setQuery("SELECT load_extension('spatialite')", dbProject);" function is recognized, but I got this message:
  error "The specified procedure could not be found.\r\nUnable to fetch row"
  If I take a look on my debug output in MSVC14, I can see that the spatialite.dll and all its dependencies have been loaded.</p>
  
  <p>Notice: I tested this with my Spatialite and also the mod_spatialite that I download form their website.</p>
  
  <p>Any ideas about this problem?
  Thanks in advance.</p>