migration: add Grantlee parser smoke test; apply safe RTI finder guard; add patch script to avoid QT_TESTCASE_BUILDDIR redefinition

cmake/FindRTI.cmake

@@ -86,7 +86,10 @@ IF(NOT RTI_DIR)
         if(_found_arch STREQUAL "")
           # fallback: pick any x64Linux* directory under lib
           file(GLOB _rti_arch_dirs RELATIVE "${_RTI_DIR}/lib" "${_RTI_DIR}/lib/x64Linux*")
-          list(GET _rti_arch_dirs 0 _found_arch)
+          list(LENGTH _rti_arch_dirs _rti_arch_dirs_len)
+          if(_rti_arch_dirs_len GREATER 0)
+            list(GET _rti_arch_dirs 0 _found_arch)
+          endif()
         endif()
         if(NOT _found_arch STREQUAL "")
           SET(_rti_gcc_arch "${_found_arch}")