Silent clang warnings.

examples/common/imgui/imgui.cpp

@@ -139,7 +139,7 @@ struct OcornutImguiContext
 					bgfx::TextureHandle th = m_texture;
 					bgfx::ProgramHandle program = m_program;
 
-					if (NULL != cmd->TextureId)
+					if (ImU64(0) != cmd->TextureId)
 					{
 						union { ImTextureID ptr; struct { bgfx::TextureHandle handle; uint8_t flags; uint8_t mip; } s; } texture = { cmd->TextureId };