Migrate PO subsystem to C++

xtoskrnl/CMakeLists.txt

@@ -60,7 +60,7 @@ list(APPEND XTOSKRNL_SOURCE
     ${XTOSKRNL_SOURCE_DIR}/mm/${ARCH}/init.c
     ${XTOSKRNL_SOURCE_DIR}/mm/${ARCH}/pages.c
     ${XTOSKRNL_SOURCE_DIR}/mm/${ARCH}/pmap.c
-    ${XTOSKRNL_SOURCE_DIR}/po/idle.c
+    ${XTOSKRNL_SOURCE_DIR}/po/idle.cc
     ${XTOSKRNL_SOURCE_DIR}/rtl/${ARCH}/dispatch.cc
     ${XTOSKRNL_SOURCE_DIR}/rtl/${ARCH}/exsup.cc
     ${XTOSKRNL_SOURCE_DIR}/rtl/atomic.cc