Abort xtrabackup on "lsn in the future" error

Summary:
This further mitigates the issue of the ibd file growing to idiotic size.

Test Plan:
Jenkins.

Going to test this in prod, with Eric's blessing.

Reviewers: santoshb

Reviewed By: santoshb
option to log only comments of a query when using RBR

Summary:
option to log only comments of a query when using RBR.
Note that comments at the beginning of the query are
logged. Other comments in the middle or end of the query
are ignored.

Test Plan: mtr tests

Reviewers: rongrong, jtolmer

Reviewed By: jtolmer
Increase UNIV_PAGE_SIZE_MAX to 32KB

Summary:
MySQL 5.6 already has support for configurable page size so bumping up
the max is all that is required for this support, unlike in 5.1.

Unlike the other allowable page sizes, the extent size was increased to
2MB in order to keep the descriptor array small enough to fit on a page.
Another option was to remove the unused XDES_CLEAN_BIT from the array but
that solution didn't work for a key block size of 1KB. Also, increasing
the extent size keeps the assert in in buf_dblwr_init that
srv_doublewrite_batch_size is < 2 * TRX_SYS_DOUBLEWRITE_BLOCK_SIZE quiet
so there was no need to reduce the batch size.

Also, at page sizes above 16KB, the offset stored in the dense directory
of compressed pages will exceed the 14 bits allocated for it by default.
Thus, 32KB pages increase the slot size to 3 bytes and give a full 2 bytes
for the offset.

Because UNIV_PAGE_SIZE has a type now ((ulint) srv__page_size) some precompile assertions
in page0zip won't work anymore. Change those to runtime assertions.

Test Plan: mtr and mtr --mysqld=--innodb-page-size=32k

Reviewers: jtolmer, steaphan

Reviewed By: jtolmer, steaphan