Fix several valgrind failures

[tgoyne]

Checking actual == 0 rather than actual < encryption_page_size resulted in us proceeding to try to hash the partial read, which if this was the very first page read with the current AESCryptor would hash uninitialized data. This was probably harmless in practice as the hmac check would fail anyway.

Not zero-initializing the hmac variable lets valgrind produce an error if we ever fail to initialize it (which did not turn out to be the problem).

The TwoPages and ThreePages were failing to test the scenarios they were intending to test when page_size() wasn't 4k. In particular, the TwoPages test would read a complete page and hit a normal decryption failure rather than an incomplete read.

Group_TableNameTooLong used uninitialized data as the table name. This was actually almost fine, but building the error message when throwing an exception involved string formatting on the uninitialized data and thus branching.

The suppressions file was super out of data and most of the things being suppressed are long-gone.

(This will need to be rebased after the release is complete to put the changelog entry in the correct place).

[coveralls-official]

Pull Request Test Coverage Report for Build thomas.goyne_398

Details

• 7 of 7 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall first build on tg/valgrind at 90.96%

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Totals
Change from base Build 2399:	91.0%
Covered Lines:	214550
Relevant Lines:	235873

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💛 - Coveralls

[ironage]

💯

[coveralls-official]

Pull Request Test Coverage Report for Build thomas.goyne_399

Details

• 7 of 7 (100.0%) changed or added relevant lines in 2 files are covered.
• 83 unchanged lines in 12 files lost coverage.
• Overall coverage decreased (-0.004%) to 90.947%

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Files with Coverage Reduction	New Missed Lines	%
src/realm/sync/network/websocket.cpp	1	71.79%
src/realm/db.cpp	2	92.05%
src/realm/object-store/shared_realm.cpp	2	91.89%
src/realm/query_expression.hpp	2	93.81%
src/realm/query_engine.cpp	3	92.36%
src/realm/sync/noinst/protocol_codec.hpp	3	73.5%
src/realm/sync/noinst/client_impl_base.cpp	4	82.67%
src/realm/sync/noinst/server/server_history.cpp	4	63.51%
test/fuzz_tester.hpp	4	57.32%
src/realm/table.cpp	5	90.16%

Totals
Change from base Build 2400:	-0.004%
Covered Lines:	214521
Relevant Lines:	235875

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💛 - Coveralls