fix some warnings

Author: jef-n

src/core/auth/qgsauthmanager.cpp

@@ -3049,6 +3049,7 @@ bool QgsAuthManager::reencryptAllAuthenticationSettings( const QString &prevpass
   return true;
   // end remove
 
+#if 0
   if ( isDisabled() )
     return false;
 
@@ -3123,6 +3124,7 @@ bool QgsAuthManager::reencryptAllAuthenticationSettings( const QString &prevpass
   }
 
   return true;
+#endif
 }
 
 bool QgsAuthManager::reencryptAllAuthenticationIdentities( const QString &prevpass, const QString &prevciv )

src/core/geometry/qgsabstractgeometryv2.cpp

@@ -227,8 +227,6 @@ QgsPointV2 QgsAbstractGeometryV2::centroid() const
   {
     return QgsPointV2( Cx / ( 3. * A ), Cy / ( 3. * A ) );
   }
-
-  return QgsPointV2();
 }
 
 bool QgsAbstractGeometryV2::isEmpty() const

src/core/geometry/qgsgeos.cpp

@@ -1652,7 +1652,6 @@ QgsAbstractGeometryV2* QgsGeos::reshapeGeometry( const QgsLineStringV2& reshapeW
     }
     CATCH_GEOS_WITH_ERRMSG( 0 )
   }
-  return 0;
 }
 
 GEOSGeometry* QgsGeos::reshapeLine( const GEOSGeometry* line, const GEOSGeometry* reshapeLineGeos )

src/core/qgsdistancearea.cpp

@@ -332,7 +332,6 @@ double QgsDistanceArea::measure( const QgsAbstractGeometryV2* geomV2 ) const
       return area;
     }
   }
-  return 0.0;
 }
 
 double QgsDistanceArea::measure( const QgsGeometry *geometry ) const