What some people don't quite get is that mingw-w64 supports LFS, and supported
it for some time (a couple of years, roughly).
LFS is controlled by an intricate set of macros, and there's a blog post[1] i
did to explore and systematize this, but in a nutshell: normal autotooled
software packages will end up using LFS, with "struct stat" having 64-bit
st_size field, regardless of OS bitness, while time fields (an issue orthogonal
to LFS) will be 32-bit on 32-bit OS and 64-bit on 64-bit OS.

gstdio.h, as of March 2010, typedefs GStatBuf as "struct stat" instead of
"struct _stat". Which means that GStatBuf will have LFS, if configure is used
(I.e. glib is built in MSYS, or cross-compiled from GNU/Linux or Cygwin).
"struct _stat" would not have had this problem, as it has 32-bit st_size field,
always.

This bug is a fork of bug 711547 (see [2]), i want it fixed soon'ish.

[1] https://gnunet.org/content/sorting-out-stat-thing
[2] https://bugzilla.gnome.org/show_bug.cgi?id=711547#c10