renamed SDL PI constants to SDL_PI_D and SDL_PI_F.

src/stdlib/SDL_stdlib.c

@@ -79,12 +79,12 @@ SDL_acos(double val)
 #else
     double result;
     if (val == -1.0) {
-        result = SDL_M_PIl;
+        result = SDL_PI_D;
     } else {
         result = SDL_atan(SDL_sqrt(1.0 - val * val) / val);
         if (result < 0.0)
         {
-            result += SDL_M_PIl;
+            result += SDL_PI_D;
         }
     }
     return result;
@@ -109,9 +109,9 @@ SDL_asin(double val)
 #else
     double result;
     if (val == -1.0) {
-        result = -(SDL_M_PIl / 2.0);
+        result = -(SDL_PI_D / 2.0);
     } else {
-        result = (SDL_M_PIl / 2.0) - SDL_acos(val);
+        result = (SDL_PI_D / 2.0) - SDL_acos(val);
     }
     return result;
 #endif