Make innochecksum work with compressed tables

make innochecksum work on compressed tables

this patch ports the work that facebook has performed
to make innochecksum handle compressed tables.
the basic idea is to use actual innodb-code to perform
checksum verification rather than duplicating in innochecksum.cc.
to make this work, innodb code has been annotated with
lots of #ifndef UNIV_INNOCHECKSUM so that it can be
compiled outside of storage/innobase.

a new testcase is also added that verifies that innochecksum
works on compressed/non-compressed tables.

the actual steps to produce this patch are:

• take innochecksum from 5.6.14
• apply changes in innodb from facebook patches needed to make innochecksum compile
• apply changes in innochecksum from facebook patches
• add handcrafted testcase

the referenced facebook patches used are:

    https://github.com/facebook/mysql-5.6/commit/91e25120e75272db4cdbc07d0e45877d9dea5715

    https://github.com/facebook/mysql-5.6/commit/847fe76ea5239b09fa361b023c56e6be76d32046

    https://github.com/facebook/mysql-5.6/commit/1135628a5a9b3412621b93233478f3804bcef51a

    https://github.com/facebook/mysql-5.6/commit/4dbf7c240ce2f08b7d6572d9452c9779ce90641c