fdo#84370 - xlsx threaded import - protect editeng.

Sadly we need to hold the solar mutex for rich text import, cue
massive lock contention on sheets packed with rich text cells;
hopefully not a common case.

Change-Id: I6a094a070b11c8b572fd8687be96110c4905e78d

sc/source/filter/oox/richstring.cxx

@@ -27,6 +27,8 @@
 #include "biffinputstream.hxx"
 #include "editutil.hxx"
 
+#include <vcl/svapp.hxx>
+
 namespace oox {
 namespace xls {
 
@@ -403,6 +405,9 @@ void RichString::convert( const Reference< XText >& rxText, bool bReplaceOld, co
     for( PortionVector::const_iterator aIt = maTextPortions.begin(), aEnd = maTextPortions.end(); aIt != aEnd; ++aIt )
         sString += (*aIt)->getText();
 
+    // fdo#84370 - diving into editeng is not thread safe.
+    SolarMutexGuard aGuard;
+
     rEE.SetText( sString );
 
     for( PortionVector::const_iterator aIt = maTextPortions.begin(), aEnd = maTextPortions.end(); aIt != aEnd; ++aIt )