vulkan: fix canvas rendering

Sometimes canvas commands wouldn't get executed.
This was because when the window gets resized,
the command buffers would get recreated, and would thus
lose the recorded commands.

src/modules/graphics/vulkan/Graphics.cpp

@@ -149,8 +149,6 @@ namespace love {
 				this->pixelHeight = pixelheight;
 
 				resetProjection();
-
-				recreateSwapChain();
 			}
 
 			bool Graphics::setMode(void* context, int width, int height, int pixelwidth, int pixelheight, bool windowhasstencil, int msaa) {

src/modules/graphics/vulkan/Graphics.h

@@ -219,7 +219,7 @@ namespace love {
 				VkPolygonMode currentPolygonMode = VK_POLYGON_MODE_FILL;
 
 				VkFormat currentFramebufferOutputFormat = VK_FORMAT_UNDEFINED;
-				Texture* renderTargetTexture = nullptr;
+				Texture* renderTargetTexture;
 				float currentViewportWidth = 0;
 				float currentViewportHeight = 0;
 			};

src/modules/graphics/vulkan/Texture.cpp

@@ -63,10 +63,10 @@ namespace love {
 						std::vector<uint8> defaultPixels;
 						defaultPixels.reserve(width * height * 4);
 						for (size_t i = 0; i < width * height; i++) {
-							// transparent white
-							defaultPixels.push_back(255);
-							defaultPixels.push_back(255);
-							defaultPixels.push_back(255);
+							// transparent black
+							defaultPixels.push_back(0);
+							defaultPixels.push_back(0);
+							defaultPixels.push_back(0);
 							defaultPixels.push_back(255);
 						}
 						Rect rect = { 0, 0, width, height };