[qt] Don't add import/export when building inside Qt plugin. (#394) (#395)

[qt] Do not add import/export into headers when building inside Qt plugin. (#394)

Co-authored-by: Tadej Novak <tadej@tano.si>

platform/qt/qt.cmake

@@ -280,12 +280,19 @@ if (MBGL_QT_STATIC AND NOT MBGL_QT_INSIDE_PLUGIN)
             $<$<NOT:$<BOOL:${MBGL_QT_WITH_INTERNAL_SQLITE}>>:Qt${QT_VERSION_MAJOR}::Sql>
             $<$<NOT:$<OR:$<PLATFORM_ID:Windows>,$<PLATFORM_ID:Emscripten>>>:z>
     )
+endif()
+
+if (MBGL_QT_STATIC OR MBGL_QT_INSIDE_PLUGIN)
+    # Don't add import/export into public header because we don't build shared library.
+    # In case on MBGL_QT_INSIDE_PLUGIN it's always OBJECT library and bundled into one
+    # single Qt plugin lib.
     target_compile_definitions(
         qmaplibregl
         PUBLIC QT_MAPLIBREGL_STATIC
     )
 endif()
 
+
 install(TARGETS qmaplibregl
         EXPORT QMapLibreGLTargets
         # Explicit set of DESTINATION is needed for older CMake versions.