mingw: be more generous when wrapping up the setitimer() emulation

Every once in a while, the Azure Pipeline fails with some semi-random error: timer thread did not terminate timely This error message means that the thread that is used to emulate the setitimer() function did not terminate within 1,000 milliseconds. The most likely explanation (and therefore the one we should assume to be true, according to Occam's Razor) is that the timeout of one second is simply not enough because we try to run so many tasks in parallel. So let's give it ten seconds instead of only one. That should be enough. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>