QDeclarative crashes with PARAM_RTP_MEM_FILL=FALSE on VxWorks

When PARAM_RTP_MEM_FILL=FALSE then VxWorks is not filling memory allocations with 0s, which cause the QML Engine crash.
5.15 had the following change:
#if OS(VXWORKS)
// page allocator expects mmap'ed memory to be zero'ed
memset(result, 0, bytes);
#endif
in reserveAndCommit()