Use floating point values for viewport, clip rectangle, and texture sizes

These are integer values internally, but the API has been changed to make it easier to mix other render code with querying those values.

Fixes https://github.com/libsdl-org/SDL/issues/7519

test/testdrawchessboard.c

@@ -32,7 +32,7 @@ static void DrawChessBoard(void)
 {
     int row = 0, column = 0, x = 0;
     SDL_FRect rect;
-    SDL_Rect darea;
+    SDL_FRect darea;
 
     /* Get the Size of drawing surface */
     SDL_GetRenderViewport(renderer, &darea);
@@ -43,10 +43,10 @@ static void DrawChessBoard(void)
         for (; column < 4 + (row % 2); column++) {
             SDL_SetRenderDrawColor(renderer, 0, 0, 0, 0xFF);
 
-            rect.w = (float)(darea.w / 8);
-            rect.h = (float)(darea.h / 8);
-            rect.x = (float)(x * rect.w);
-            rect.y = (float)(row * rect.h);
+            rect.w = (darea.w / 8);
+            rect.h = (darea.h / 8);
+            rect.x = (x * rect.w);
+            rect.y = (row * rect.h);
             x = x + 2;
             SDL_RenderFillRect(renderer, &rect);