Solved the bug that caused the rtkUpsampleImageFilter to freeze when multithreaded.
Solved the bug that caused the rtkUpsampleImageFilter to freeze when
multithreaded.

fabienmomey/RTK,ldqcarbon/RTK,dsarrut/RTK,SimonRit/RTK,ldqcarbon/RTK,ipsusila/RTK,ipsusila/RTK,ipsusila/RTK,SimonRit/RTK,dsarrut/RTK,fabienmomey/RTK,fabienmomey/RTK,ipsusila/RTK,dsarrut/RTK,ldqcarbon/RTK,fabienmomey/RTK,fabienmomey/RTK,dsarrut/RTK,SimonRit/RTK,ipsusila/RTK,ldqcarbon/RTK,ipsusila/RTK,fabienmomey/RTK,dsarrut/RTK,SimonRit/RTK,ldqcarbon/RTK,fabienmomey/RTK,dsarrut/RTK,ldqcarbon/RTK,ipsusila/RTK,dsarrut/RTK,ldqcarbon/RTK