tdf#125153 vcl: fix ImplReadDIBFileHeader()

Apparently the offset needs to be checked against the total size
of the stream, not against the remaining size.

(regression from b67d9a5d)

Change-Id: I7e714b7c4ce34b5285cfbf9ca81133ecbbb16fc1
Reviewed-on: https://gerrit.libreoffice.org/71903
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>
(cherry picked from commit 34d12802)
Reviewed-on: https://gerrit.libreoffice.org/71917Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>

vcl/source/gdi/dibtools.cxx

@@ -1053,7 +1053,7 @@ bool ImplReadDIBFileHeader( SvStream& rIStm, sal_uLong& rOffset )
 {
     bool bRet = false;
 
-    const sal_uInt64 nStreamLength = rIStm.remainingSize();
+    const sal_uInt64 nStreamLength = rIStm.TellEnd();
 
     sal_uInt16 nTmp16 = 0;
     rIStm.ReadUInt16( nTmp16 );