CONFIG -= plugin if shared_app.pri links to it.

Index: src/3rdparty/legacy/spatialindexnavel/spatialindexnavel.pro
--- src/3rdparty/legacy/spatialindexnavel/spatialindexnavel.pro.orig
+++ src/3rdparty/legacy/spatialindexnavel/spatialindexnavel.pro
@@ -6,7 +6,7 @@ r_static_libs {
     CONFIG += staticlib
 }
 else {
-    CONFIG += plugin
+    #CONFIG += plugin
 }
 
 # this is required to compile the spatial index library from navel ltd:
