Fix cspptrie deadlock & cleanups

[noobpwnftw]

It is incorrect to replace opportunistic locks by unlocking without restoring old locking state.

@royguo This passes your unit test at 8-threads.

Minor cleanups to boost-include and remove one false positive assert.

[royguo]

Hi, @noobpwnftw , consider the db_bench test here:

./output/db_bench
--benchmarks=fillseq 
--use_existing_db=0 
--sync=0         
--db=$PWD/data_terarkdb     
--wal_dir=$PWD/data_terarkdb        
--bytes_per_sync=65536            
--wal_bytes_per_sync=65536            
--num=1011305            
--threads=10     
--num_levels=6            
--delayed_write_rate=209715200       
--key_size=100          
--value_size=2000       
--cache_numshardbits=6          
--level_compaction_dynamic_level_bytes=true     
--cache_index_and_filter_blocks=1       
--pin_l0_filter_and_index_blocks_in_cache=0     
--benchmark_write_rate_limit=0          
--hard_rate_limit=3     
--rate_limit_delay_max_milliseconds=1000000     
--write_buffer_size=268435456           
--max_write_buffer_number=6     
--target_file_size_base=134217728       
--max_bytes_for_level_base=536870912            
--verify_checksum=1     
--delete_obsolete_files_period_micros=62914560         
--max_bytes_for_level_multiplier=10     
--statistics=0          
--stats_per_interval=1          
--stats_interval_seconds=60     
--histogram=1           
--open_files=-1         
--level0_file_num_compaction_trigger=4          
--level0_slowdown_writes_trigger=1000           
--level0_stop_writes_trigger=1000            
--num_high_pri_threads=3            
--num_low_pri_threads=10
--mmap_read=true            
--compression_type=none            
--memtablerep=patricia_trie                                      
--use_terark_table=false                          
--blob_size=128 
--allow_concurrent_memtable_write=false

If we set allow_concurrent_memtable_write to true, the program will crash on an assertion. Seems something goes wrong inside CSPPTrie. @mm304321141 @levisonchen Please keep an eye on this PR.