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!