fix valgrind error in erts/emulator/drivers/unix/ttsl_drv.c
fix valgrind error in erts/emulator/drivers/unix/ttsl_drv.c

Running some valgrind memory checking showed the error below:

==18040== Thread 6:
==18040== Source and destination overlap in memcpy(0xf3f3f04, 0xf3f3f08, 52)
==18040==    at 0x4C2CFA0: memcpy@@GLIBC_2.14 (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==18040==    by 0x5CF527: del_chars (ttsl_drv.c:845)
==18040==    by 0x5CED5E: ttysl_from_erlang (ttsl_drv.c:658)
==18040==    by 0x4982E3: erts_write_to_port (io.c:1235)
==18040==    by 0x49A2BD: erts_port_command (io.c:2223)
==18040==    by 0x48C054: do_send (bif.c:1962)
==18040==    by 0x48CB6E: erl_send (bif.c:2162)
==18040==    by 0x566599: process_main (beam_emu.c:1665)
==18040==    by 0x4B1A95: sched_thread_func (erl_process.c:4834)
==18040==    by 0x6075E2: thr_wrapper (ethread.c:106)
==18040==    by 0x5560E99: start_thread (pthread_create.c:308)

This occurred on Linux using R15B01 while the shell was emitting a prompt,
but the same problem is still present in R16B.

Change the memcpy on line 845 of ttsl_drv.c to memmove as valgrind
suggests. After the change, verify with valgrind that the error no longer
occurs.

lrascao/otp,lemenkov/otp,sammoth-wazoku/otp,RichMorin/otp,ader1990/otp,dgud/otp,palas/otp,isvilen/otp,jemsbhai/otp,yangchengjian/otp,lrascao/otp,weisslj/otp,electricimp/otp,jj1bdx/otp,lianghaivv/otp,jinshana/otp,VincentHHL/otp,bsmr-erlang/otp,beni55/otp,electricimp/otp,bjorng/otp,johanclaesson/otp,ferd/otp,massemanet/otp,sitexa/otp,isvilen/otp,mikpe/otp,benoitc/otp-1,krishnakumar4a4/otp,platinumthinker/otp,aboroska/otp,msantos/otp,klarna/otp,mikpe/otp,lantti/otp,lantti/otp,release-project/otp,erlang/otp,lhslll/otp,c-rack/otp,basho/otp,VincentHHL/otp,cobusc/otp,theom/otp,uabboli/otp,saleyn/otp,electricimp/otp,paladim/otp,bjorng/otp,cobusc/otp,tuncer/otp,stolen/otp,jinshana/otp,bernardd/otp,jamesruan/otp,mikpe/otp,ahmedshafeeq/otp,gjaldon/otp,mikpe/otp,jinshana/otp,vinoski/otp,cobusc/otp,fenollp/otp,cnbin/otp,haguenau/otp,vinoski/otp,matwey/otp,bjorng/otp,sitexa/otp,RGafiyatullin/otp,schlagert/otp,ferd/otp,bernardd/otp,c-rack/otp,hairyhum/otp,VincentHHL/otp,electricimp/otp,RJ/otp,potatosalad/otp,Teino1978-Corp/otp,cnbin/otp,psyeugenic/otp,msantos/otp,derek121/otp,jemsbhai/otp,schlagert/otp,hairyhum/otp,psyeugenic/otp,enikki/otp,bugs-erlang-org/otp,hairyhum/otp,sdebnath/otp,krishnakumar4a4/otp,basho/otp,psyeugenic/otp,GinjaNinja32/otp,legoscia/otp,jamesruan/otp,kvakvs/otp,ader1990/otp,tuncer/otp,dgud/otp,emile/otp,RoadRunnr/otp,sdebnath/otp,ferd/otp,bernardd/otp,bjorng/otp,massemanet/otp,release-project/otp,release-project/otp,lucafavatella/otp,sammoth-wazoku/otp,klarna/otp,saleyn/otp,vic/otp,legoscia/otp,marquisthunder/otp,cnbin/otp,getong/otp,saleyn/otp,Teino1978-Corp/erlang-otp,klarna/otp,enikki/otp,jj1bdx/otp,platinumthinker/otp,RJ/otp,emile/otp,VincentHHL/otp,NOMORECOFFEE/otp,ferd/otp,msantos/otp,lianghaivv/otp,lemenkov/otp,kvakvs/otp,marquisthunder/otp,ahmedshafeeq/otp,c-rack/otp,ferd/otp,RoadRunnr/otp,isvilen/otp,lianghaivv/otp,krishnakumar4a4/otp,riverrun/otp,palas/otp,paulcager/otp,potatosalad/otp,jinshana/otp,RaimoNiskanen/otp,uabboli/otp,weisslj/otp,dumbbell/otp,paulcager/otp,kvakvs/otp,lucafavatella/otp,isvilen/otp,aboroska/otp,lucafavatella/otp,jj1bdx/otp,paulcager/otp,tuncer/otp,krishnakumar4a4/otp,RoadRunnr/otp,GinjaNinja32/otp,mujiatong/otp,massemanet/otp,riverrun/otp,RichMorin/otp,VincentHHL/otp,Teino1978-Corp/otp,matwey/otp,marquisthunder/otp,bsmr-erlang/otp,msantos/otp,release-project/otp,bernardd/otp,sitexa/otp,ader1990/otp,cobusc/otp,neeraj9/otp,benoitc/otp-1,saleyn/otp,falkevik/otp,fenollp/otp,rlipscombe/otp,johanclaesson/otp,matwey/otp,ader1990/otp,goertzenator/otp,msantos/otp,getong/otp,RichMorin/otp,benoitc/otp-1,lantti/otp,fenollp/otp,VincentHHL/otp,ferd/otp,derek121/otp,rlipscombe/otp,uabboli/otp,c-rack/otp,jj1bdx/otp,mikpe/otp,schlagert/otp,lianghaivv/otp,goertzenator/otp,stolen/otp,psyeugenic/otp,lucafavatella/otp,RGafiyatullin/otp,neeraj9/otp,lightcyphers/otp,erlang/otp,ahmedshafeeq/otp,tuncer/otp,RichMorin/otp,ferd/otp,isvilen/otp,emacsmirror/erlang,GinjaNinja32/otp,basho/otp,massemanet/otp,g-andrade/otp,schlagert/otp,RJ/otp,RGafiyatullin/otp,lantti/otp,matwey/otp,dgud/otp,schlagert/otp,legoscia/otp,ader1990/otp,msantos/otp,theom/otp,theom/otp,falkevik/otp,cobusc/otp,matwey/otp,emile/otp,lightcyphers/otp,tuncer/otp,RJ/otp,johanclaesson/otp,RaimoNiskanen/otp,RaimoNiskanen/otp,massemanet/otp,electricimp/otp,getong/otp,mujiatong/otp,marquisthunder/otp,bsmr-erlang/otp,release-project/otp,bugs-erlang-org/otp,RoadRunnr/otp,bugs-erlang-org/otp,schlagert/otp,falkevik/otp,legoscia/otp,lhslll/otp,jinshana/otp,lightcyphers/otp,dumbbell/otp,falkevik/otp,bsmr-erlang/otp,msantos/otp,kvakvs/otp,lhslll/otp,enikki/otp,dumbbell/otp,lhslll/otp,ahmedshafeeq/otp,erlang/otp,haguenau/otp,yangchengjian/otp,release-project/otp,Teino1978-Corp/erlang-otp,paulcager/otp,hairyhum/otp,lantti/otp,platinumthinker/otp,electricimp/otp,Teino1978-Corp/erlang-otp,RichMorin/otp,uabboli/otp,jamesruan/otp,jinshana/otp,riverrun/otp,g-andrade/otp,jj1bdx/otp,lantti/otp,lhslll/otp,Teino1978-Corp/erlang-otp,lemenkov/otp,weisslj/otp,benoitc/otp-1,haguenau/otp,basho/otp,lrascao/otp,Teino1978-Corp/otp,lianghaivv/otp,lrascao/otp,lemenkov/otp,stolen/otp,jamesruan/otp,stolen/otp,sdebnath/otp,cobusc/otp,vladdu/otp,erlang/otp,mujiatong/otp,bugs-erlang-org/otp,lemenkov/otp,rlipscombe/otp,isvilen/otp,RGafiyatullin/otp,saleyn/otp,uabboli/otp,RoadRunnr/otp,RaimoNiskanen/otp,awetzel/otp,RJ/otp,vinoski/otp,RJ/otp,lightcyphers/otp,ahmedshafeeq/otp,sitexa/otp,electricimp/otp,emacsmirror/erlang,theom/otp,matwey/otp,mujiatong/otp,goertzenator/otp,jemsbhai/otp,emile/otp,riverrun/otp,RoadRunnr/otp,NOMORECOFFEE/otp,vladdu/otp,cobusc/otp,marquisthunder/otp,dumbbell/otp,vladdu/otp,vladdu/otp,electricimp/otp,awetzel/otp,vinoski/otp,palas/otp,jemsbhai/otp,uabboli/otp,RichMorin/otp,basho/otp,aboroska/otp,getong/otp,erlang/otp,yangchengjian/otp,paulcager/otp,aboroska/otp,lrascao/otp,goertzenator/otp,enikki/otp,g-andrade/otp,RichMorin/otp,psyeugenic/otp,mujiatong/otp,g-andrade/otp,sitexa/otp,bugs-erlang-org/otp,lucafavatella/otp,bjorng/otp,isvilen/otp,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