[Solaris 10 64-bit] Qt 4.8.7: cmalloc crash from javascriptcore with CC 5.12

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 1 (LWP 1)]
0xfffffd7ffe9d68ce in __1cRTCMalloc_PageMap34ibK_GEnsure6MLL_b_ ()
   from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
(gdb) bt
#0  0xfffffd7ffe9d68ce in __1cRTCMalloc_PageMap34ibK_GEnsure6MLL_b_ ()
   from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#1  0xfffffd7ffe9d4347 in __1cFQdDTWTFRTCMalloc_PageHeapIGrowHeap6ML_b_ ()
   from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#2  0xfffffd7ffe9d6d00 in __1cFQdDTWTFRTCMalloc_PageHeapDNew6ML_pn0AESpan__ ()
   from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#3  0xfffffd7ffe9d5fb0 in __1cFQdDTWTFZTCMalloc_Central_FreeListIPopulate6M_v_
    () from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#4  0xfffffd7ffe9d4bfe in __1cFQdDTWTFZTCMalloc_Central_FreeListSFetchFromSpansSafe6M_pv_ () from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#5  0xfffffd7ffe9d4ae7 in __1cFQdDTWTFZTCMalloc_Central_FreeListLRemoveRange6Mppv3pi_v_ () from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#6  0xfffffd7ffe9d6dd7 in __1cFQdDTWTFUTCMalloc_ThreadCacheIAllocate6ML_pv_ ()
   from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#7  0xfffffd7ffe9d5a82 in __1cFQdDTWTFJdo_malloc4B_6FL_pv_ ()
   from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#8  0xfffffd7ffe9d8599 in __1cFQdDTWTFTinitializeThreading6F_v_ ()
   from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#9  0xfffffd7ffe9727a9 in __1cFQdDTJSCXinitializeThreadingOnce6F_v_ ()
   from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#10 0xfffffd7ffe9727da in __1cFQdDTJSCTinitializeThreading6F_v_ ()
   from /export/home/support/Qt/qt-4.8.7-stl64/lib/libQtScript.so.4
#11 0xfffffd7ffe9f9afd in __1cUQdDScriptEnginePrivate2t6M_v_ ()