main-loop: Fix build for w32 and w64

This patch fixes a build regression with MinGW which was introduced by
commit 7c7db75576bd5a31508208f153c5aada64b2c8df.

The 3rd argument of g_main_context_query must point to a gint value.
Using a pointer to an uint32_t value is wrong.

The timeout argument of function os_host_main_loop_wait was never
used for w32 / w64.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
