make faild with this error... gcc -shared sql_mysql.lo -L/usr/lib -L/usr/lib/mysql /usr/lib/libmysqlclient.so -lz -lm -lssl -lcrypto -Wl,-soname -Wl,rlm_sql_mysql-1.0.1.so -o .libs/rlm_sql_mysql-1.0.1.so /usr/bin/ld: cannot find -lz collect2: ld returned 1 exit status gmake[10]: *** [rlm_sql_mysql.la] Error 1 What is -lz ?