test have delay on first time on gd based terminals on native windows

[Tatsuro M. <tma...@ya...>]

Hello

This is not a bug but and an annoying matter.

On gnuplot 5 (5.0, 5.2, 5.3) on gd based terminals, test has delay for first try

set term png
set out 'test.png'
test # delay more than 30 seconds for me


second execution test does not take time

On gnuplot 4.6.7, delay does not happen.

Any suggestions?

Tatsuro