Description of problem:
net-snmp src rpm contains a bad patch that breaks building the rpm on systems without systemd.

Version-Release number of selected component (if applicable):
net-snmp-5.7.3-25.1.fc27.src.rpm (and likely older versions as well)

How reproducible:
always

Steps to Reproduce:
1. try to build srpm on RHEL/CentOS 6
2.
3.

Actual results:
.libs/snmpd.o: In function `main':
/builddir/build/BUILD/net-snmp-5.7.3/agent/snmpd.c:459: undefined reference to `netsnmp_sd_listen_fds'

Expected results:
no errors

Additional info:
Fix is pretty easy:

--- ../sources/net-snmp-5.7.2-systemd.patch.orig        2018-02-15 17:20:49.271208819 -0500
+++ ../sources/net-snmp-5.7.2-systemd.patch     2018-02-15 17:21:09.691126055 -0500
@@ -82,10 +82,10 @@
  #endif

  #ifndef WIN32
-+#ifndef NETSNMP_NO_SYSYSTEMD
++#ifndef NETSNMP_NO_SYSTEMD
 +    /* check if systemd has sockets for us and don't close them */
 +    prepared_sockets = netsnmp_sd_listen_fds(0);
-+#endif /* NETSNMP_NO_SYSYSTEMD */
++#endif /* NETSNMP_NO_SYSTEMD */
 +
      /*
       * close all non-standard file descriptors we may have