coverity#982478 Dereference after null check

maybe sort of can be considered a regression from
commit 733b831970204059b9d89eff203551d6d3bf4bbe
Date:   Tue Jan 5 16:37:41 2010 +0100
    swunolocking1: swtypes.hxx: rename frame anchor types
     enum RndStdIds: rename frame anchor types (FLY_*) to be more intuitive.

where

if (0 == (pAnchorPos = pAnch->GetCntntAnchor()))
    bCallMake = sal_False;

turned to

if (pAnchorPos)
    bCallMake = sal_False;

but there would always be a following de-ref of a potential NULL pAnchorPos
which wasn't FLY_AT_PAGE

Change-Id: I808b4f178887ab6149e38bab6e36eb68d7a1eb29
Resolves: fdo#85032 max len property of -1 -> crash

Change-Id: Ief903c619204f01784e93fd5e2d582632cef032e