Fix mistaken memory leak tidy up

* Sort of confused false positive - some pipeline SPIR-V blobs were
  leaking but it was because they weren't being cached when they should
  have, not because saving the shader cache doesn't destroy its blobs.

renderdoc/driver/d3d11/d3d11_debug.cpp

@@ -164,9 +164,11 @@ D3D11DebugManager::~D3D11DebugManager()
     SaveShaderCache("d3dshaders.cache", m_ShaderCacheMagic, m_ShaderCacheVersion, m_ShaderCache,
                     ShaderCacheCallbacks);
   }
-
-  for(auto it = m_ShaderCache.begin(); it != m_ShaderCache.end(); ++it)
-    ShaderCacheCallbacks.Destroy(it->second);
+  else
+  {
+    for(auto it = m_ShaderCache.begin(); it != m_ShaderCache.end(); ++it)
+      ShaderCacheCallbacks.Destroy(it->second);
+  }
 
   ShutdownFontRendering();
   ShutdownStreamOut();

renderdoc/driver/vulkan/vk_debug.cpp

@@ -2101,9 +2101,11 @@ VulkanDebugManager::~VulkanDebugManager()
     SaveShaderCache("vkshaders.cache", m_ShaderCacheMagic, m_ShaderCacheVersion, m_ShaderCache,
                     ShaderCacheCallbacks);
   }
-
-  for(auto it = m_ShaderCache.begin(); it != m_ShaderCache.end(); ++it)
-    ShaderCacheCallbacks.Destroy(it->second);
+  else
+  {
+    for(auto it = m_ShaderCache.begin(); it != m_ShaderCache.end(); ++it)
+      ShaderCacheCallbacks.Destroy(it->second);
+  }
 
   for(auto it = m_PostVSData.begin(); it != m_PostVSData.end(); ++it)
   {