Fixed assert in perfschema/pfs.cc::start_idle_wait_v1 when using performance schema and big packets in debug version.

The bug was that my_real_read() called net_before_header_psi() multiple times for long packets.
Fixed by adding a flag when we are reading a header.
Did also some cleanups to interface of my_net_read() to avoid unnecessary calls if performance schema is not used.

- Added my_net_read_packet() as a replacement for my_net_read(). my_net_read() is still in the client library for old clients.
- Removed THD->m_server_idle (not needed anymore as this is now given as argument to my_net_read_packet()
- Added my_net_read_packet(), which is a new version of my_net_read() with a new parameter if we are doing a read for a new command from the server.
- Added tests for compressed protocol and big packets





include/mysql.h.pp:
  Added my_net_read_packet() as a replacement for my_net_read()
include/mysql_com.h:
  Added my_net_read_packet() as a replacement for my_net_read()
mysql-test/r/mysql_client_test_comp.result:
  New test
mysql-test/t/mysql_client_test-master.opt:
  Added max_allowed_packet to be able to test big packets and packet size overflows.
mysql-test/t/mysql_client_test_comp-master.opt:
  New test
mysql-test/t/mysql_client_test_nonblock-master.opt:
  Added max_allowed_packet to be able to test big packets and packet size overflows.
sql-common/client.c:
  Use my_net_read_packet()
sql/mf_iocache.cc:
  Use my_net_read_packet()
sql/mysqld.cc:
  Removed THD->m_server_idle (not needed anymore as this is now given as argument to my_net_read_packet()
sql/net_serv.cc:
  Added argument to my_real_read() to indicte if we are reading the first block of the next statement and should call performance schema.
  Added 'compatibilty function' my_net_read().
  Added my_net_read_packet(), which is a new version of my_net_read() with a new parameter if we are doing a read for a new command from the server.
sql/sql_class.cc:
  Removed m_server_idle (not needed anymore)
sql/sql_class.h:
  Removed m_server_idle (not needed anymore)
sql/sql_parse.cc:
  Removed m_server_idle (not needed anymore)
tests/mysql_client_test.c:
  Added tests for compressed protocol and big packets