Fix Windows build failures on AppVeyor

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FAILED TEST SUMMARY

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MongoDB\BSON\toJSON(): Encoding JSON [C:\projects\mongo-php-driver\tests\bson\bson-toJSON-001.phpt]

MongoDB\Driver\Query construction (invalid maxAwaitTimeMS range) [C:\projects\mongo-php-driver\tests\query\query-ctor_error-006.phpt]

MongoDB\Driver\ReadPreference construction (invalid maxStalenessSeconds range) [C:\projects\mongo-php-driver\tests\readPreference\readpreference-ctor_error-004.phpt]

TEST 1185/1747 [C:\projects\mongo-php-driver\tests\bson\bson-toJSON-001.phpt]

========DIFF========

007+ { "nan" : -nan(ind) }

007- { "nan" : nan }

========DONE========

FAIL MongoDB\BSON\toJSON(): Encoding JSON [C:\projects\mongo-php-driver\tests\bson\bson-toJSON-001.phpt]

TEST 1547/1747 [C:\projects\mongo-php-driver\tests\query\query-ctor_error-006.phpt]

========DIFF========

001+ FAILED: Expected MongoDB\Driver\Exception\InvalidArgumentException thrown, but no exception thrown!

002+ 

001- OK: Got MongoDB\Driver\Exception\InvalidArgumentException

002- Expected "maxAwaitTimeMS" option to be <= 4294967295, 4294967296 given

========DONE========

FAIL MongoDB\Driver\Query construction (invalid maxAwaitTimeMS range) [C:\projects\mongo-php-driver\tests\query\query-ctor_error-006.phpt]

TEST 1573/1747 [C:\projects\mongo-php-driver\tests\readPreference\readpreference-ctor_error-004.phpt]

========DIFF========

002+ Expected maxStalenessSeconds to be >= 90, -2147483648 given

002- Expected maxStalenessSeconds to be <= 2147483647, 2147483648 given

========DONE========

FAIL MongoDB\Driver\ReadPreference construction (invalid maxStalenessSeconds range) [C:\projects\mongo-php-driver\tests\readPreference\readpreference-ctor_error-004.phpt]