sbbscon.c: In function ‘whoami’:
sbbscon.c:430: warning: implicit declaration of function ‘getresuid’
sbbscon.c:432: warning: implicit declaration of function ‘getresgid’
sbbscon.c: In function ‘linux_keepcaps’:
sbbscon.c:452: warning: implicit declaration of function ‘prctl’
sbbscon.c:447: warning: unused variable ‘strbuf’