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

include/SSystem/SComponent/c_m3d.h

@@ -1,7 +1,7 @@
 #ifndef C_M3D_H_
 #define C_M3D_H_
 
-#include "math.h"
+#include <math.h>
 #include "dolphin/mtx.h"
 
 class cM3dGAab;

include/SSystem/SComponent/c_xyz.h

@@ -2,7 +2,7 @@
 #define C_XYZ_H
 
 #include "dolphin/mtx.h"
-#include "math.h"
+#include <math.h>
 
 struct cXyz : Vec {
     static const cXyz Zero;