move writer class for reuse in memory status page

Summary: Move the writer class so that it can be reused for the memory status page. This also have an initial class for the memory status page which will be populated with metrics on in later diffs.

Reviewed By: @edwinsmith

Differential Revision: D1505623
Streamline destructor call

Summary: Using baseless mode, and a memory operand instead of a load
saves two instructions for the table-lookup destructor
call sequence.

Reviewed By: @bertmaher

Differential Revision: D1503998
Compile warning in ipc format

Summary: Cygwin's sysv ipc layer uses a long long int for key_t which makes for noise when compiling
And I hate warnings

Reviewed By: @JoelMarcey

Differential Revision: D1502077
Revert "Merge pull request #3516 from MaideCa/thirdparty_sqlite_386"

This reverts commit eb5a264803fab4e8c974b6fd68522c83fc3ac263, reversing
changes made to 8a9a63d5af72bc37ceb12dea57834c8af41a52a7.