Fix gcc warning "ignoring return value of ..."

Fix gcc warning "ignoring return value of ..."

This patch fixes two warnings of gcc 4.4.3 when used with eglibc 2.11.1:

ngircd.c: In function ‘NGIRCd_Init’:
ngircd.c:801: warning: ignoring return value of ‘chdir’, declared with
 attribute warn_unused_result
conn.c: In function ‘Simple_Message’:
conn.c:2041: warning: ignoring return value of ‘write’, declared with
 attribute warn_unused_result

The first by checking the return code and an appropriate error message,
the second by "better" ignoring it (which is correct there!) ...