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_kankyo.cpp

@@ -24,26 +24,12 @@
 #include "f_op/f_op_kankyo.h"
 #include "m_Do/m_Do_graphic.h"
 #include "m_Do/m_Do_lib.h"
-
-#if DEBUG
-extern "C" int atoi(const char* str);
-extern "C" f32 atof(const char* str);
-#endif
+#include <stdlib.h>
 
 static void GxXFog_set();
 
 struct sub_kankyo__class : public kankyo_class {};
 
-// setSunpos calls these functions as inlines somehow
-// these need to be moved to MSL_C once an appropriate solution is found
-inline float sinf(float x) {
-    return sin(x);
-}
-
-inline float cosf(float x) {
-    return cos(x);
-}
-
 static LightStatus lightStatusBase = {
     {-36384.5f, 29096.699f, 17422.199f},
     {377.0f, 5207.3999f, 1220.4f},