fix math.h

Declare sin/cos and M_PI in math.h.

components/libc/minilibc/math.c

@@ -9,7 +9,6 @@
  */
 
 #define PRECISION 9
-#define M_PI 3.141592653589793238462643
 
 static double cos_off_tbl[] = {0.0, -M_PI/2., 0, -M_PI/2.};
 static double cos_sign_tbl[] = {1,-1,-1,1};

components/libc/minilibc/math.h

-#ifndef __STDIO_H__
-#define __STDIO_H__
+#ifndef __MATH_H__
+#define __MATH_H__
+
+#define M_PI 3.141592653589793238462643
+
+double sin(double x);
+double cos(double x);
 
 #endif