Merge pull request #23417 from souch:souch-fix-parallel-backend-example

fix cmakelists of parallel backend example
closes https://github.com/opencv/opencv/issues/23376

samples/cpp/tutorial_code/core/parallel_backend/CMakeLists.txt

@@ -5,9 +5,9 @@ find_package(OpenCV REQUIRED COMPONENTS opencv_core)
 if(NOT OPENCV_EXAMPLES_SKIP_PARALLEL_BACKEND_OPENMP
     AND NOT OPENCV_EXAMPLES_SKIP_OPENMP
 )
+  project(opencv_example_openmp_backend)
   find_package(OpenMP)
   if(OpenMP_FOUND)
-    project(opencv_example_openmp_backend)
     add_executable(opencv_example_openmp_backend example-openmp.cpp)
     target_link_libraries(opencv_example_openmp_backend PRIVATE
         opencv_core
@@ -20,13 +20,13 @@ if(NOT OPENCV_EXAMPLES_SKIP_PARALLEL_BACKEND_TBB
     AND NOT OPENCV_EXAMPLES_SKIP_TBB
     AND NOT OPENCV_EXAMPLE_SKIP_TBB  # deprecated (to be removed in OpenCV 5.0)
 )
+  project(opencv_example_tbb_backend)
   find_package(TBB QUIET)
   if(NOT TBB_FOUND)
     find_path(TBB_INCLUDE_DIR NAMES "tbb/tbb.h")
     find_library(TBB_LIBRARY NAMES "tbb")
   endif()
   if(TBB_INCLUDE_DIR AND TBB_LIBRARY)
-    project(opencv_example_tbb_backend)
     add_executable(opencv_example_tbb_backend example-tbb.cpp)
     target_include_directories(opencv_example_tbb_backend SYSTEM PRIVATE ${TBB_INCLUDE_DIR})
     target_link_libraries(opencv_example_tbb_backend PRIVATE