message: Add M_PI #define for platforms that do not have that defined.
diff: @@ -21,6 +21,11 @@ limitations under the License.
  #include <stdlib.h>
  #include <string.h>
  +// Some platforms don't have M_PI
  +#ifndef M_PI
  +#define M_PI 3.14159265358979323846
  +#endif
  +
  void WindowFillConfigWithDefaults(struct WindowConfig* config) {
  config->size_ms = 25;
  config->step_size_ms = 10;
  