CMakeLists.txt: make 2 variables configurable

Variables PREFERRED_PYTHON_PATH and PYTHON3_PATH are set with
${PYTHON_EXECUTABLE}. For cross compile, ${PYTHON_EXECUTABLE} may point
to other path rather than standard dir such as /usr/bin. Then the
generated library file contains such path which should NOT. Update to
make variables PREFERRED_PYTHON_PATH and PYTHON3_PATH configurable to
avoid such issue.

Signed-off-by: Kai Kang <[email protected]>

Author: kkang-wr

CMakeLists.txt

@@ -125,8 +125,8 @@ endif()
 find_package(PythonInterp 3)
 find_package(PythonLibs 3)
 
-set(PREFERRED_PYTHON_PATH "${PYTHON_EXECUTABLE}")
-set(PYTHON3_PATH "${PYTHON_EXECUTABLE}")
+set(PREFERRED_PYTHON_PATH "${PYTHON_EXECUTABLE}" CACHE PATH "Path to preferred Python")
+set(PYTHON3_PATH "${PYTHON_EXECUTABLE}" CACHE PATH "Path to Python3")
 
 find_package(RPM)
 if(RPM_FOUND)