PERF: Avoid temporary smartptr in ProcessObject::GetInput
PERF: Avoid temporary smartptr in ProcessObject::GetInput

ProcessObject::GetInput() uses a conditional operator with different
value types on its two branches, which leads to a temporary object of
the common type (SmartPointer) being created.

This can impact performance if some code calls GetInput() in a loop,
like WarpImageFilter currently does.

Since the method returns a raw pointer anyway, we can explicitly call
GetPointer(), avoiding the short-lived smart pointer instances.

Change-Id: I1602e0e76a8391dd592decc731117f832ba0fdba

LucasGandel/ITK,spinicist/ITK,malaterre/ITK,Kitware/ITK,Kitware/ITK,biotrump/ITK,vfonov/ITK,BRAINSia/ITK,biotrump/ITK,stnava/ITK,richardbeare/ITK,hjmjohnson/ITK,InsightSoftwareConsortium/ITK,richardbeare/ITK,malaterre/ITK,stnava/ITK,stnava/ITK,thewtex/ITK,thewtex/ITK,hjmjohnson/ITK,Kitware/ITK,zachary-williamson/ITK,Kitware/ITK,jcfr/ITK,LucasGandel/ITK,blowekamp/ITK,fbudin69500/ITK,blowekamp/ITK,hjmjohnson/ITK,PlutoniumHeart/ITK,malaterre/ITK,PlutoniumHeart/ITK,malaterre/ITK,biotrump/ITK,vfonov/ITK,LucasGandel/ITK,LucasGandel/ITK,richardbeare/ITK,fbudin69500/ITK,spinicist/ITK,hjmjohnson/ITK,BRAINSia/ITK,hjmjohnson/ITK,zachary-williamson/ITK,thewtex/ITK,stnava/ITK,thewtex/ITK,stnava/ITK,InsightSoftwareConsortium/ITK,PlutoniumHeart/ITK,BRAINSia/ITK,InsightSoftwareConsortium/ITK,richardbeare/ITK,thewtex/ITK,Kitware/ITK,jcfr/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,hjmjohnson/ITK,vfonov/ITK,biotrump/ITK,vfonov/ITK,PlutoniumHeart/ITK,LucasGandel/ITK,malaterre/ITK,malaterre/ITK,spinicist/ITK,BRAINSia/ITK,malaterre/ITK,zachary-williamson/ITK,vfonov/ITK,zachary-williamson/ITK,LucasGandel/ITK,jcfr/ITK,PlutoniumHeart/ITK,fbudin69500/ITK,BRAINSia/ITK,Kitware/ITK,biotrump/ITK,stnava/ITK,fbudin69500/ITK,vfonov/ITK,BRAINSia/ITK,spinicist/ITK,hjmjohnson/ITK,spinicist/ITK,spinicist/ITK,spinicist/ITK,fbudin69500/ITK,biotrump/ITK,richardbeare/ITK,blowekamp/ITK,zachary-williamson/ITK,thewtex/ITK,zachary-williamson/ITK,Kitware/ITK,stnava/ITK,jcfr/ITK,malaterre/ITK,blowekamp/ITK,InsightSoftwareConsortium/ITK,fbudin69500/ITK,richardbeare/ITK,spinicist/ITK,vfonov/ITK,stnava/ITK,blowekamp/ITK,InsightSoftwareConsortium/ITK,blowekamp/ITK,LucasGandel/ITK,InsightSoftwareConsortium/ITK,PlutoniumHeart/ITK,biotrump/ITK,fbudin69500/ITK,jcfr/ITK,fbudin69500/ITK,spinicist/ITK,vfonov/ITK,richardbeare/ITK,zachary-williamson/ITK,zachary-williamson/ITK,jcfr/ITK,blowekamp/ITK,LucasGandel/ITK,vfonov/ITK,jcfr/ITK,malaterre/ITK,stnava/ITK,jcfr/ITK,thewtex/ITK,InsightSoftwareConsortium/ITK,blowekamp/ITK,biotrump/ITK,BRAINSia/ITK,zachary-williamson/ITK