* Removed WITH_WSREP_SR_SPEEDUP_REPLAY and DEBUG_SR_SPEEDUP_REPLAY
* Added "--wsrep_SR_store=undolog" for enabling SR speedup
* Modified MTR tests "galera_sr.GCF-572" and
"galera_sr.galera_sr_cc_master"
* Improved the code that removes unneeded fragments from
binlog_fragment_cache.
Now all galera_sr tests succeed when SR speedup is disabled
and most galera_sr MTR tests succeed when SR speedup up is enabled.
The failing tests are listed in "skipped_tests" file.
The following MTR test suite run succeeds:
(cd mysql-test; ./mysql-test-run.pl --mysqld="--wsrep_SR_store=undolog"
--suite=galera_sr --skip-test-list=../skipped_tests --force)