Fix warnings in MSVC 2010.

src/common/math.h

@@ -66,7 +66,7 @@ struct vertex
 	float x, y;
 	float s, t;
 };
-	
+
 inline int next_p2(int x)
 {
 	x += (x == 0);
@@ -75,6 +75,11 @@ inline int next_p2(int x)
 	return ++x;
 }
 
+inline float next_p2(float x)
+{
+	return static_cast<float>(next_p2(static_cast<int>(x)));
+}
+
 } // love
 
 #endif // LOVE_MATH_H