Dear Kadir,
I am going to write and compile some others, see the facts, and after putting them in a strict formal manner, I will send them to the MinGW developers and here.
Thank you for doing that.
I find that the same Pascal code will compile under Cigwin and run with microseconds displayed correctly.
I tried the older Pascal compiler (20060215) in MinGW and obtained the same problem: microseconds is always zero.
So I think you're probably right: the problem is with MinGW.
Yours, Kevan