MonClient: pass function parameter by reference

[src/mon/MonClient.h:412]: (performance) Function parameter 'mon_name'
  should be passed by reference.

Changed also parameter name in function implementation to match name
in declaration.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
BarrierContext: reduce scope of 'done' variable

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
BarrierContext: prefer prefix ++operator for non-trivial iterator

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
Monitor: pass function parameter by reference

[src/mon/Monitor.h:619]: (performance) Function parameter 'param_str_map'
  should be passed by reference.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
ceph_argparse.cc: prefer prefix ++operator for non-trivial iterator

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
Client.cc: use !empty() instead of size()

[src/client/Client.cc:2275]: (performance) Possible inefficient
  checking for 'cap_snaps' emptiness.
[src/client/Client.cc:2458]: (performance) Possible inefficient
  checking for 'cap_snaps' emptiness.
[src/client/Client.cc:2986]: (performance) Possible inefficient
  checking for 'caps' emptiness.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
str_map.cc: prefer prefix ++operator for non-trivial iterator

[src/common/str_map.cc:55]: (performance) Prefer prefix ++/-- operators
  for non-primitive types.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
common/config.cc: prefer prefix ++operator for non-trivial iterator

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
Client: remove a std::string::c_str() calls

[src/client/Client.cc:6821]: (performance) Passing the result of c_str() to a
  function that takes std::string as argument no. 2 is slow and redundant.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
PGLog.h: prefer prefix ++operator for non-trivial iterator

[src/osd/PGLog.h:363]: (performance) Prefer prefix ++/-- operators for
  non-primitive types.
[src/osd/PGLog.h:375]: (performance) Prefer prefix ++/-- operators for
  non-primitive types.
[src/osd/PGLog.h:380]: (performance) Prefer prefix ++/-- operators for
  non-primitive types.
[src/osd/PGLog.h:382]: (performance) Prefer prefix ++/-- operators for
  non-primitive types.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
CrushWrapper: prefer prefix ++operator for non-trivial iterator

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
CrushWrapper::is_valid_crush_loc(): pass function parameter by reference

[src/crush/CrushWrapper.cc:1412]: (performance) Function parameter 'loc'
  should be passed by reference.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
MDCache: prefer prefix ++operator for non-trivial iterator

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
OSDMonitor: use !empty() instead of size() > 0

[src/mon/OSDMonitor.cc:730]: (performance) Possible inefficient checking
  for 'osd_weight' emptiness.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
OSDMonitor: prefer prefix ++operator for non-trivial iterator

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
DBObjectMap: use !empty() instead of size()

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
FileStore: use !empty() instead of size()

[src/os/FileStore.cc:3635]: (performance) Possible inefficient checking
  for 'omap_set' emptiness.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
KeyValueStore: use !empty() instead of size()

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
KeyValueStore: prefer prefix ++operator for non-trivial iterator

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
RPCRecPred: use !empty() instead of size() >= 1

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>