Remove unnecessary locking which was blocking for store ios.
Remove unnecessary locking which was blocking for store ios.

This is safe because the main thread is the only one which
sets the SegmentInfo state, because no recovery thread is
started before setRecovering() completes, and because
segmentId is const.

Fixes RAM-214.

taschik/ramcloud-load-manager,rstutsman/RAMCloud,taschik/ramcloud,jblomer/ramcloud,anirajk/RAMCloud,anirajk/RAMCloud,QingkaiLu/RAMCloud,matrix207/RAMCloud,mrdiegoa/ramcloud,QingkaiLu/RAMCloud,SMatsushi/RAMCloud,matrix207/RAMCloud,anirajk/RAMCloud,rstutsman/RAMCloud,DavidLi2010/ramcloud,mrdiegoa/ramcloud,jblomer/ramcloud,IMCG/RamCloud,jblomer/ramcloud,matrix207/RAMCloud,taschik/ramcloud-load-manager,Frank-Wu/RamCloud,matrix207/RAMCloud,SMatsushi/RAMCloud,jcarreira/ramcloud,taschik/ramcloud-load-manager,y-higuchi/ramcloud,utah-scs/RAMCloud,taschik/ramcloud,utah-scs/RAMCloud,SMatsushi/RAMCloud,QingkaiLu/RAMCloud,utah-scs/RAMCloud,y-higuchi/ramcloud,taschik/ramcloud,alexandermerritt/ramcloud,mrdiegoa/ramcloud,utah-scs/RAMCloud,Frank-Wu/RamCloud,DavidLi2010/ramcloud,rstutsman/RAMCloud,y-higuchi/ramcloud,matrix207/RAMCloud,jcarreira/ramcloud,behnamm/cs244b_project,anirajk/RAMCloud,alexandermerritt/ramcloud,utah-scs/RAMCloud,IMCG/RamCloud,y-higuchi/ramcloud,alexandermerritt/ramcloud,alexandermerritt/ramcloud,DavidLi2010/ramcloud,jcarreira/ramcloud,Frank-Wu/RamCloud,QingkaiLu/RAMCloud,DavidLi2010/ramcloud,DavidLi2010/ramcloud,matrix207/RAMCloud,behnamm/cs244b_project,taschik/ramcloud-load-manager,behnamm/cs244b_project,SMatsushi/RAMCloud,Frank-Wu/RamCloud,IMCG/RamCloud,SMatsushi/RAMCloud,jblomer/ramcloud,taschik/ramcloud,QingkaiLu/RAMCloud,alexandermerritt/ramcloud,y-higuchi/ramcloud,rstutsman/RAMCloud,DavidLi2010/ramcloud,rstutsman/RAMCloud,IMCG/RamCloud,jcarreira/ramcloud,anirajk/RAMCloud,anirajk/RAMCloud,taschik/ramcloud-load-manager,mrdiegoa/ramcloud,jcarreira/ramcloud,taschik/ramcloud,behnamm/cs244b_project,Frank-Wu/RamCloud,Frank-Wu/RamCloud,alexandermerritt/ramcloud,jblomer/ramcloud,IMCG/RamCloud,jblomer/ramcloud,QingkaiLu/RAMCloud,y-higuchi/ramcloud,SMatsushi/RAMCloud,rstutsman/RAMCloud,mrdiegoa/ramcloud,mrdiegoa/ramcloud,IMCG/RamCloud,behnamm/cs244b_project,utah-scs/RAMCloud,behnamm/cs244b_project,jcarreira/ramcloud