Remove spurious assert

Remove nop assert that causes warnings on Clang.

imgui.cpp

@@ -828,7 +828,6 @@ void ImGui::ColorConvertHSVtoRGB(float h, float s, float v, float& out_r, float&
 static bool ImLoadFileToMemory(const char* filename, const char* file_open_mode, void** out_file_data, size_t* out_file_size, size_t padding_bytes)
 {
     IM_ASSERT(filename && file_open_mode && out_file_data && out_file_size);
-    IM_ASSERT(padding_bytes >= 0);
     *out_file_data = NULL;
     *out_file_size = 0;