VideoBackends/Null: Remove unnecessary constructors and destructors

Removes constructors and destructors that don't actually provide any
behavior (i.e. doesn't constain generated code related to non-trivial
members in a cpp file, etc).

Lessens the amount of code present.

Source/Core/VideoBackends/Null/NullTexture.h

@@ -19,7 +19,6 @@ class NullTexture final : public AbstractTexture
 {
 public:
   explicit NullTexture(const TextureConfig& config);
-  ~NullTexture() = default;
 
   void CopyRectangleFromTexture(const AbstractTexture* src,
                                 const MathUtil::Rectangle<int>& src_rect, u32 src_layer,
@@ -58,7 +57,6 @@ public:
   explicit NullFramebuffer(AbstractTexture* color_attachment, AbstractTexture* depth_attachment,
                            AbstractTextureFormat color_format, AbstractTextureFormat depth_format,
                            u32 width, u32 height, u32 layers, u32 samples);
-  ~NullFramebuffer() override = default;
 
   static std::unique_ptr<NullFramebuffer> Create(NullTexture* color_attachment,
                                                  NullTexture* depth_attachment);

Source/Core/VideoBackends/Null/PerfQuery.h

@@ -11,8 +11,6 @@ namespace Null
 class PerfQuery : public PerfQueryBase
 {
 public:
-  PerfQuery() {}
-  ~PerfQuery() override {}
   void EnableQuery(PerfQueryGroup type) override {}
   void DisableQuery(PerfQueryGroup type) override {}
   void ResetQuery() override {}

Source/Core/VideoBackends/Null/Render.cpp

@@ -44,7 +44,6 @@ class NullShader final : public AbstractShader
 {
 public:
   explicit NullShader(ShaderStage stage) : AbstractShader(stage) {}
-  ~NullShader() = default;
 };
 
 std::unique_ptr<AbstractShader>
@@ -61,9 +60,6 @@ std::unique_ptr<AbstractShader> Renderer::CreateShaderFromBinary(ShaderStage sta
 
 class NullPipeline final : public AbstractPipeline
 {
-public:
-  NullPipeline() = default;
-  ~NullPipeline() override = default;
 };
 
 std::unique_ptr<AbstractPipeline> Renderer::CreatePipeline(const AbstractPipelineConfig& config,

Source/Core/VideoBackends/Null/TextureCache.h

@@ -10,10 +10,6 @@ namespace Null
 {
 class TextureCache : public TextureCacheBase
 {
-public:
-  TextureCache() {}
-  ~TextureCache() {}
-
 protected:
   void CopyEFB(AbstractStagingTexture* dst, const EFBCopyParams& params, u32 native_width,
                u32 bytes_per_row, u32 num_blocks_y, u32 memory_stride,