cmake(python): handle PYTHON3_LIMITED_API

- python-3.x => python-3
- config-3.x.py => config-3.py

modules/python/common.cmake

@@ -164,7 +164,12 @@ if(OPENCV_SKIP_PYTHON_LOADER)
   endif()
 else()
   ocv_assert(DEFINED OPENCV_PYTHON_INSTALL_PATH)
-  set(__python_binary_install_path "${OPENCV_PYTHON_INSTALL_PATH}/${__python_loader_subdir}python-${${PYTHON}_VERSION_MAJOR}.${${PYTHON}_VERSION_MINOR}")
+  if(${PYTHON}_LIMITED_API)
+    set(__python_binary_subdir "python-${${PYTHON}_VERSION_MAJOR}")
+  else()
+    set(__python_binary_subdir "python-${${PYTHON}_VERSION_MAJOR}.${${PYTHON}_VERSION_MINOR}")
+  endif()
+  set(__python_binary_install_path "${OPENCV_PYTHON_INSTALL_PATH}/${__python_loader_subdir}${__python_binary_subdir}")
 endif()
 
 install(TARGETS ${the_module}
@@ -192,7 +197,7 @@ if(NOT OPENCV_SKIP_PYTHON_LOADER)
     set(CMAKE_PYTHON_EXTENSION_INSTALL_PATH_BASE "LOADER_DIR")
   endif()
 
-  if(DEFINED ${PYTHON}_VERSION_MINOR)
+  if(DEFINED ${PYTHON}_VERSION_MINOR AND NOT ${PYTHON}_LIMITED_API)
     set(__target_config "config-${${PYTHON}_VERSION_MAJOR}.${${PYTHON}_VERSION_MINOR}.py")
   else()
     set(__target_config "config-${${PYTHON}_VERSION_MAJOR}.py")