common thread-related minor functions in new .h file

executables/nr-gnb.c

executables/nr-ru.c

executables/nr-softmodem.c

executables/nr-softmodem.h

executables/nr-uesoftmodem.c

executables/softmodem-common.h

executables/thread-common.h

openair1/PHY/LTE_TRANSPORT/dlsch_coding.c

openair1/SIMULATION/LTE_PHY/dlsim.c

openair1/SIMULATION/LTE_PHY/ulsim.c

openair2/ENB_APP/enb_config.c

openair2/GNB_APP/gnb_config.c

targets/RT/USER/lte-enb.c

targets/RT/USER/lte-ru.c

targets/RT/USER/lte-softmodem-common.c

targets/RT/USER/lte-uesoftmodem.c