[azchohfi]

On Windows, poll() in compat/poll/poll.c waits with MsgWaitForMultipleObjects() and pumps
window messages with PeekMessage(), TranslateMessage() and DispatchMessage(). These are the
only functions git.exe imports from user32.dll, so every Git process loads user32, and with it
gdi32, gdi32full, win32u and imm32, even though most commands never call poll().

This loads the four functions with the existing lazyload.h helpers the first time poll() runs.
If user32 cannot be loaded, the process cannot have a message queue to pump, so it waits with
WaitForMultipleObjects().

git.exe then maps 17 images for git --version instead of 23. On a Windows 11 desktop, built
from v2.55.0.windows.5 with and without the change, 100 interleaved runs each:

	before	after	saved
git --version	15.5 ms	13.2 ms	2.2 ms [2.0, 2.4]
git rev-parse --git-dir	17.5 ms	15.2 ms	2.3 ms [2.0, 2.4]
git status --short	48.5 ms	46.2 ms	2.0 ms [1.7, 2.2]
git log -1 --oneline	20.4 ms	18.0 ms	2.3 ms [2.0, 2.5]

t0061-run-command, t5400-send-pack and t5601-clone pass with the change, on the release and
on main.

The same code is in upstream Git, so I can send it to the mailing list too if you prefer it to go
upstream first.

I used GitHub Copilot to help investigate and prepare this change. I have reviewed and tested it.