[#2207] Re-ordered null check before dereference, removed unused var

STACK Output:
bug: anti-dce
model: |
  %cmp20 = icmp eq %struct.DataObjInfo* null, %srcDataObjInfo.0, !dbg !4104, !macro !4106
  -->  false
  ************************************************************
  if.then21:
  call void (i32, i8*, ...)* @rodsLog(i32 3, i8* getelementptr inbounds ([44 x i8]* @.str158, i32 0, i32 0)), !dbg !4107
  br label %return, !dbg !4109
stack:
  - /home/kellerb/software/root-stack/irods/iRODS/server/api/src/rsDataObjRepl.cpp:768:0
ncore: 1
core:
  - /home/kellerb/software/root-stack/irods/iRODS/server/api/src/rsDataObjRepl.cpp:756:0
    - null pointer dereference