They are probably sometimes used by the bteam

just in case old linux is used, add _GNU_SOURCE preprocessor constant to be able to see pthread_rwlock_t

-lm is sometimes not linked, which causes errors about undefined rint()
- FreeBSD embedded library does not link with the flags returned by mysql_config
 (added -lcrypt to LIBS, whereby causing overlinking in case of normal non-embedded client)

for regular PB builds.

Init MY_PTHREAD_MUTEX_FAST prior to first usage to avoid crash on
FreeBSD

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honor OUTPUT_NAME in MERGE_LIBRARIES macro

        
Problem: The test case failed because: (i) warning text in 
         result file differed from the warning output by the 
         server, and (ii) binlog contents in result file did
         not show the statements logged wrapped in BEGIN/COMMIT
         as it is the case after WL 2687.
      
Solution: We update the result file, but first we change the
          unsafe warning text to also refer to performance_schema
          table(s). This required changing the result files for
          existing test cases that provide output for warnings 
          related to ER_BINLOG_UNSAFE_SYSTEM_TABLE. "Grepping" in
          result files, shows that only binlog_unsafe contained
          reference to such a warning.
      
          We also update the result file with the missing 
          BEGIN/COMMIT statements.

DISABLE_MYSQL_THREAD_H for strings
Also, enable unittests for perfschema

Conflicts:
  Text conflict in sql/sql_insert.cc 

STMT mode aborts the SQL Thread if it receives changes in ROW mode and such
changes are not processed.

add WITH_MYSQLD_LIBS for extra linker flags for mysqld