Review some issues on standalone mode

src/raylib.h

@@ -1331,7 +1331,6 @@ RLAPI Texture2D GetShapesTexture(void);                                   // Get
 RLAPI Rectangle GetShapesTextureRec(void);                                // Get texture rectangle to draw shapes
 RLAPI void SetShapesTexture(Texture2D texture, Rectangle source);         // Define default texture used to draw shapes
 
-
 // Shader configuration functions
 RLAPI int GetShaderLocation(Shader shader, const char *uniformName);      // Get shader uniform location
 RLAPI void SetShaderValue(Shader shader, int uniformLoc, const void *value, int uniformType);               // Set shader uniform value

src/rlgl.h

@@ -198,6 +198,14 @@ typedef unsigned char byte;
         unsigned char b;
         unsigned char a;
     } Color;
+    
+    // Rectangle type
+    typedef struct Rectangle {
+        float x;
+        float y;
+        float width;
+        float height;
+    } Rectangle;
 
     // Texture2D type
     // NOTE: Data stored in GPU memory