List: Fix out of bound errors
List: Fix out of bound errors

This change should remove the following run-time errors reported by the
address sanitizer:

    list.c:365:10: runtime error: index 3 out of bounds for type
                                  'GetPlacements [3]'
    SUMMARY: AddressSanitizer: undefined-behavior
    list.c:383:10: runtime error: index 4 out of bounds for type
                                  'SetPlacements [4]'
    SUMMARY: AddressSanitizer: undefined-behavior

.

This commit fixes #1461.

ElektraInitiative/libelektra,mpranj/libelektra,petermax2/libelektra,ElektraInitiative/libelektra,ElektraInitiative/libelektra,petermax2/libelektra,mpranj/libelektra,petermax2/libelektra,ElektraInitiative/libelektra,ElektraInitiative/libelektra,mpranj/libelektra,BernhardDenner/libelektra,petermax2/libelektra,e1528532/libelektra,petermax2/libelektra,ElektraInitiative/libelektra,BernhardDenner/libelektra,BernhardDenner/libelektra,e1528532/libelektra,petermax2/libelektra,mpranj/libelektra,mpranj/libelektra,petermax2/libelektra,mpranj/libelektra,ElektraInitiative/libelektra,e1528532/libelektra,e1528532/libelektra,e1528532/libelektra,mpranj/libelektra,BernhardDenner/libelektra,mpranj/libelektra,ElektraInitiative/libelektra,petermax2/libelektra,BernhardDenner/libelektra,mpranj/libelektra,e1528532/libelektra,BernhardDenner/libelektra,ElektraInitiative/libelektra,petermax2/libelektra,ElektraInitiative/libelektra,BernhardDenner/libelektra,e1528532/libelektra,mpranj/libelektra,e1528532/libelektra,BernhardDenner/libelektra,ElektraInitiative/libelektra,BernhardDenner/libelektra,mpranj/libelektra