Exclude Qt source files from coverage results.

CTestCustom.cmake.in

@@ -53,4 +53,7 @@ SET(CTEST_CUSTOM_COVERAGE_EXCLUDE
 
   # Exclude try_compile sources from coverage results:
   "/CMakeFiles/CMakeTmp/"
+
+  # Exclude Qt source files from coverage results:
+  "[A-Za-z]./[Qq]t/qt-.+-opensource-src"
   )