MSL_C header cleanup (#2988)

* msl_c header cleanup

* math header cleanup

* fix rest of shieldD configs

* cleanup cflag configs a bit

* fix shield build

src/d/d_com_inf_game.cpp

@@ -22,7 +22,7 @@
 #include "m_Do/m_Do_Reset.h"
 #include "m_Do/m_Do_controller_pad.h"
 #include "m_Do/m_Do_graphic.h"
-#include "stdio.h"
+#include <stdio.h>
 
 void dComIfG_play_c::ct() {
     mWindowNum = 0;