Make all file access 64-bit (uint64_t)

This changes the types of a big number of variables.

General rules:
- Using `uint64_t` in general. We also considered `int64_t` but eventually
  settled on keeping it unsigned, which is also closer to what one would expect
  with `size_t`/`off_t`.
- We only keep `int64_t` for `seek_end` (takes a negative offset from the end)
  and for the `Variant` bindings, since `Variant::INT` is `int64_t`. This means
  we only need to guard against passing negative values in `core_bind.cpp`.
- Using `uint32_t` integers for concepts not needing such a huge range, like
  pages, blocks, etc.

In addition:
- Improve usage of integer types in some related places; namely, `DirAccess`,
  core binds.

Note:
- On Windows, `_ftelli64` reports invalid values when using 32-bit MinGW with
  version < 8.0. This was an upstream bug fixed in 8.0. It breaks support for
  big files on 32-bit Windows builds made with that toolchain. We might add a
  workaround.

Fixes #44363.
Fixes godotengine/godot-proposals#400.

Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/windows/dir_access_windows.cpp b/drivers/windows/dir_access_windows.cpp
index 2c9f28717d..5aa777757f 100644
--- a/drivers/windows/dir_access_windows.cpp
+++ b/drivers/windows/dir_access_windows.cpp
@@ -325,14 +325,15 @@ FileType DirAccessWindows::get_file_type(const String& p_file) const {
 }
 
 */
-size_t DirAccessWindows::get_space_left() {
+
+uint64_t DirAccessWindows::get_space_left() {
 	uint64_t bytes = 0;
 	if (!GetDiskFreeSpaceEx(nullptr, (PULARGE_INTEGER)&bytes, nullptr, nullptr)) {
 		return 0;
 	}
 
 	//this is either 0 or a value in bytes.
-	return (size_t)bytes;
+	return bytes;
 }
 
 String DirAccessWindows::get_filesystem_type() const {