Fix modified_time on Android

[Alex2782]

Fixes: #101007 (Workaround)

Issue Description:
After saving, all timestamps (st_mtime, st_ctime, st_atime) are set to the same value.
After exporting or after some time, only modified_time resets to a past timestamp.

Cache files are created during export and rely on modified_time.

Workaround:
Use created_time if modified_time is in the past.

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#101007 (comment)
I initially suspected thirdparty/minizip/unzip.c because the timestamps were only reset after unz* functions. However, this behavior also occurs when no export is performed, once even when the Godot Editor was not running (terminated).

Test

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screen-recording-20250220-161402_t6S8GUBK.mp4

timestamp check after export

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After saving the time was still 16:xx and after export it was reset to 15:xx.

[Alex2782]

@syntaxerror247 Does this workaround also work on your device?

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Notice:

My first pull request wasn't accepted, there were these check warnings for Android. All other operating systems were not affected.

Error: drivers/unix/file_access_unix.cpp:348:21: error: 
comparison of integers of different signs: 'uint64_t' (aka 'unsigned long') and 
'__kernel_old_time_t' (aka 'long') [-Werror,-Wsign-compare]
                if (modified_time < status.st_ctime) {
                    ~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~
1 error generated.
scons: *** [drivers/unix/file_access_unix.android.editor.arm64.o] Error 1

[syntaxerror247]

Works as expected.

[akien-mga]

Thanks!

[Alex2782]

st_ctime is not created_time.

The effects need to be examined in more detail, a few days ago I noticed that this timestamp was updated outside of Godot.

alex@localhost godot-github % adb shell "stat sdcard/Documents/starter-kit-city-builder"
  File: sdcard/Documents/starter-kit-city-builder
  Size: 3488	 Blocks: 7	 IO Blocks: 512	 directory
Device: 62h/98d	 Inode: 547529	 Links: 11	 Device type: 0,0
Access: (0770/drwxrwx---)	Uid: (    0/    root)	Gid: ( 9997/everybody)
Access: 2024-07-21 13:06:31.602339129 +0200
Modify: 2024-07-21 13:06:48.914339123 +0200
Change: 2024-07-21 13:06:48.914339123 +0200

[syntaxerror247]

st_ctime updated when files metadata updates. So, if its metadata is updated due to any reason st_ctime would update. I thinks, it's not a problem for us as this would just create a new file_cache at export.

It is working in our usecase because when file is modified its size changes which probably triggers a st_ctime update.