uClibc compatibility (#5270)

* uclibc compatibility

Adds compatibility with uclibc, the officially supported toolchain of the luckfox pico

* Explicitly link stdc++fs for std::filesystem

Bringing this over from buildroot-meshtastic

src/modules/PositionModule.cpp

@@ -16,10 +16,7 @@
 #include "meshtastic/atak.pb.h"
 #include "sleep.h"
 #include "target_specific.h"
-
-extern "C" {
 #include <Throttle.h>
-}
 
 PositionModule *positionModule;