Probleme d'installation des bibliotheque s

Bonjour,
j'ai un probleme lors de l'installation de la bibliotheque zlib-1.2.3.tar.gz et aussi le logiciel libpcap... il me donne ce message lors de linstallation

[root@localhost zlib-1.2.3]# ./configure
Checking for gcc...
Building static library libz.a version 1.2.3 with cc.
Checking for unistd.h... No.
Checking whether to use vs[n]printf() or s[n]printf()... using s[n]printf()
Checking for snprintf() in stdio.h... No.
WARNING: snprintf() not found, falling back to sprintf(). zlib
can build but will be open to possible buffer-overflow security
vulnerabilities.
Checking for return value of sprintf()... No.
WARNING: apparently sprintf() does not return a value. zlib
can build but will be open to possible string-format security
vulnerabilities.
Checking for errno.h... No.
Checking for mmap support... No.