mon/OSDMonitor: some cleanup for reweight-by-pg

[tanghaodong25]

Signed-off-by: Haodong Tang haodong.tang@intel.com

[tchaikov]

[ RUN      ] CompressionPlugin.all
2017-02-16 18:43:30.106773 7ff23fc2dec0 -1 load failed dlopen(): "/home/jenkins-build/build/workspace/ceph-pull-requests/build/lib/compressor/libceph_invalid.so: cannot open shared object file: No such file or directory" or "/home/jenkins-build/build/workspace/ceph-pull-requests/build/lib/libceph_invalid.so: cannot open shared object file: No such file or directory"
*** Caught signal (Segmentation fault) **
 in thread 7ff23fc2dec0 thread_name:unittest_compre
 ceph version 12.0.0-461-ge0a84f5 (e0a84f53dc9c3c1ce88cabfcbb3262a882a63a64)
 1: (()+0x67d47) [0x7ff23fa2dd47]
 2: (()+0x10330) [0x7ff23f593330]
 3: (std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release()+0x36) [0x7ff23f9fb986]
 4: (CompressionPlugin_all_Test::TestBody()+0x9ed) [0x7ff23f9f8bad]
 5: (void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*)+0x33) [0x7ff23fa25983]
 6: (testing::Test::Run()+0xb7) [0x7ff23fa18d57]
 7: (testing::TestInfo::Run()+0x9e) [0x7ff23fa18dfe]
 8: (testing::TestCase::Run()+0xa5) [0x7ff23fa18f05]
 9: (testing::internal::UnitTestImpl::RunAllTests()+0x248) [0x7ff23fa191b8]
 10: (testing::UnitTest::Run()+0x54) [0x7ff23fa19474]
 11: (main()+0x11c) [0x7ff23f9f3f9c]
 12: (__libc_start_main()+0xf5) [0x7ff235fe9f45]
 13: (()+0x2e486) [0x7ff23f9f4486]
2017-02-16 18:43:30.107641 7ff23fc2dec0 -1 *** Caught signal (Segmentation fault) **
 in thread 7ff23fc2dec0 thread_name:unittest_compre

see https://jenkins.ceph.com/job/ceph-pull-requests/18585/consoleFull#116358421777933967-90d1-4877-8d60-89cb08ef4eb1

retest this please.

[tchaikov]

http://pulpito.ceph.com/kchai-2017-02-18_07:48:13-rados-wip-kefu-testing-2---basic-smithi/