FindPythonLibs: stop scanning when libraries are found

Modules/FindPythonLibs.cmake

@@ -134,6 +134,10 @@ FOREACH(_CURRENT_VERSION ${_Python_VERSIONS})
                          PYTHONLIBS_VERSION_STRING "${python_version_str}")
     UNSET(python_version_str)
   ENDIF(PYTHON_INCLUDE_DIR AND EXISTS "${PYTHON_INCLUDE_DIR}/patchlevel.h")
+
+  IF(PYTHON_LIBRARY AND PYTHON_INCLUDE_DIR)
+    BREAK()
+  ENDIF(PYTHON_LIBRARY AND PYTHON_INCLUDE_DIR)
 ENDFOREACH(_CURRENT_VERSION)
 
 MARK_AS_ADVANCED(