[#2207] Fixed null check

STACK Output:
bug: anti-dce
model: |
  %cmp = icmp eq %struct.MsParam* %buf_msp, null, !dbg !2437
  -->  false
  ************************************************************
  land.lhs.true:
  %inOutStruct = getelementptr inbounds %struct.MsParam* %buf_msp, i32 0, i32 2, !dbg !2437
  %0 = icmp eq %struct.MsParam* %buf_msp, null
  call void @opt.bugon(i1 %0), !dbg !2437, !bug !2439
  %1 = load i8** %inOutStruct, align 8, !dbg !2437
  %cmp1 = icmp eq i8* %1, null, !dbg !2437
  br i1 %cmp1, label %if.then, label %if.end, !dbg !2437
stack:
  - /home/kellerb/software/root-stack/irods/iRODS/server/re/src/nre.systemMS.cpp:1037:0
ncore: 1
core:
  - /home/kellerb/software/root-stack/irods/iRODS/server/re/src/nre.systemMS.cpp:1037:0
    - null pointer dereference