test/file_extract_test.rb: fix test_extract_incorrect_size in s390x arch

[lucaskanashiro]

Using the current pack directives makes test_extract_incorrect_size fail
in s390x architecture because of the endian probably. This is the output
of the command executed by the test in amd64:

irb(main):001:0> [501, 500000, 1].pack('LLS')
=> "\xF5\x01\x00\x00 \xA1\a\x00\x01\x00"

And the output of the same command in s390x:

irb(main):001:0> [501, 500000, 1].pack('LLS')
=> "\x00\x00\x01\xF5\x00\a\xA1 \x00\x01"

Changing to 'V' pack directive like is used in
lib/zib/central_directory.rb fixes the test in s390x and does not add a
regression in amd64.

FTR I've faced this issue in ruby-zip Debian package in Ubuntu, here is the log: https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-focal/focal/s390x/r/ruby-zip/20200323_152440_d8d79@/log.gz

[coveralls]

Coverage remained the same at 95.769% when pulling 262ba00 on lucaskanashiro:fix-test-in-s390x into 382cc84 on rubyzip:master.

[jdleesmiller]

Thanks for the patch and for your work on Debian!

The LLS directives coded for 'long-long-short', whereas V3 codes for 'long-long-long'. So, I think this is the right idea, but the last directive should be v for 'short'.

This matches the zip entry pack (the three directives before the final v for extra):

rubyzip/lib/zip/entry.rb

Lines 293 to 296 in 51a3b21

	zip64 && zip64.compressed_size ? 0xFFFFFFFF : @compressed_size,
	zip64 && zip64.original_size ? 0xFFFFFFFF : @size,
	name_size,
	@extra ? @extra.local_size : 0].pack('VvvvvvVVVvv')