Resolves: tdf#93461 captions laid out behind images

regression from...

commit 8a08f686
Author: Mike <mikekaganski@hotmail.com>
Date:   Mon Apr 27 01:27:05 2015 +1000

    tdf#66141: SwTxtFrm::FormatQuick(bool) endless loop

    If a line happens to be invisible (e.g. in too thin cell of a table)
    then aLine.FormatLine(nStart) returns nStart, and
    aLine.Insert( new SwLineLayout() ) is executed until OOM.

keep the zero advance loop detection attempt, but allow the first
insertion and disallow subsequent inserts

Change-Id: I16380588220149cfd0ed0f835f08d2849180fece
(cherry picked from commit f06508e2)
Reviewed-on: https://gerrit.libreoffice.org/18908Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>

sw/source/core/text/frmform.cxx

@@ -1909,12 +1909,20 @@ bool SwTextFrm::FormatQuick( bool bForceQuickFormat )
     sal_Int32 nStart = GetOfst();
     const sal_Int32 nEnd = GetFollow()
                       ? GetFollow()->GetOfst() : aInf.GetText().getLength();
+
+    int nLoopProtection = 0;
     do
     {
-        sal_Int32 nShift = aLine.FormatLine(nStart) - nStart;
-        nStart += nShift;
-        if ((nShift != 0) // Check for special case: line is invisible,
-                          // like in too thin table cell: tdf#66141
+        sal_Int32 nNewStart = aLine.FormatLine(nStart);
+        if (nNewStart == nStart)
+            ++nLoopProtection;
+        else
+            nLoopProtection = 0;
+        nStart = nNewStart;
+        const bool bWillEndlessInsert = nLoopProtection > 2;
+        SAL_WARN_IF(bWillEndlessInsert, "sw", "loop detection triggered");
+        if ((!bWillEndlessInsert) // Check for special case: line is invisible,
+                                  // like in too thin table cell: tdf#66141
          && (aInf.IsNewLine() || (!aInf.IsStop() && nStart < nEnd)))
             aLine.Insert( new SwLineLayout() );
     } while( aLine.Next() );