Description:
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For files >4gb filesize returns negative values (seems that it overwrites the sign bit -> becomes negative)

Same is with 2gb files and 32bit oses, but that has not been confirmed yet. 

Reproduce code:
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echo filesize('foo.bar');

//if foo.bar is > 4gb it returns a negative value

Expected result:
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something like 5234556

Actual result:
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something like -3456634