abaixo, alguem sabe como corrigir isso, Obrigado
# make cc checkq.c -o checkq ./checkq cc -s -O qmailmrtg7.c -o qmailmrtg7 qmailmrtg7.c: In function ‘main’: qmailmrtg7.c:69: warning: incompatible implicit declaration of built-in function ‘exit’ qmailmrtg7.c:93: warning: incompatible implicit declaration of built-in function ‘exit’ qmailmrtg7.c:131: warning: incompatible implicit declaration of built-in function ‘exit’ qmailmrtg7.c:137: warning: incompatible implicit declaration of built-in function ‘exit