Those have been there since around 2001. They're in a piece of code
that calls get_fullscreen_rect to find the overall screen size, and
then prevents attempts to resize the window larger than that. The
static variables were arranging that we don't have to call
get_fullscreen_rect more than once.
But, firstly, computers are faster 20 years on; secondly, remote
window-resize requests are intentionally rate-limited (as of commit
d74308e90e3813a), so this shouldn't be the limiting factor anyway; and
thirdly, multi-monitor support has appeared since then, which means
that if the window has been dragged from one monitor to another then
get_fullscreen_rect might _legitimately_ return a different bounding
rectangle when called a second time.
So we should just do the full check every time unconditionally.
(cherry picked from commit 4b3a8cbf61ce4ee19227784ba27c52a9e47774fb)
b8473f0c11