Fixed some invalid conversions from 'const char *' to 'char *'

common/serror.cpp

h/Ctape_api.h

h/rfio_api.h

h/rfio_errno.h

h/rtcp_server.h

h/serrno.h

rfio/error.c

rfio/rfio_calls.c

rtcopy/rtcpd_Ctape.c

rtcopy/rtcpd_GetClientInfoMsg.c

rtcopy/rtcpd_MainCntl.c

rtcopy/rtcpd_SendAckToVdqmOrTapeBridge.c

rtcopy/rtcpd_TapeIO.c

tape/Ctape_dmpfil.c

tape/readlbl.c

tape/skiptape.c

tape/tperror.c