check for net-snmp-config when buildin check_snmp (fixes #2281) (#2286)HEADmaster

this will fix the build error on check_snmp when net-snmp-config is not available.

```
  CC       check_snmp-check_snmp.o
/bin/bash: line 1: net-snmp-config: command not found
In file included from check_snmp.d/check_snmp_helpers.h:3,
                 from check_snmp.c:42:
check_snmp.d/./config.h:16:10: fatal error: net-snmp/net-snmp-config.h: No such file or directory
   16 | #include <net-snmp/net-snmp-config.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make[3]: *** [Makefile:3353: check_snmp-check_snmp.o] Error 1
make[3]: Leaving directory '/opt/projects/git/monitoring-plugins/plugins'
```

Signed-off-by: Sven Nierlein <sven@consol.de>

1 files changed, 13 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 4facfca2..41b39c7b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1445,6 +1445,19 @@ else
         AC_MSG_WARN([Get smbclient from Samba.org to monitor SMB shares])
 fi
 
+AC_PATH_PROG(PATH_TO_NETSNMPCONFIG,net-snmp-config)
+AC_ARG_WITH(netsnmpconfig_command,
+            ACX_HELP_STRING([--with-net-snmp-config-command=PATH],
+                            [sets path to net-snmp-config]),
+            PATH_TO_NETSNMPCONFIG=$withval)
+if test -n "$PATH_TO_NETSNMPCONFIG"
+then
+        AC_DEFINE_UNQUOTED(PATH_TO_NETSNMPCONFIG,"$PATH_TO_NETSNMPCONFIG",[path to net-snmp-config binary])
+        EXTRAS="$EXTRAS check_snmp"
+else
+        AC_MSG_WARN([Install net-snmp-config to build check_snmp])
+fi
+
 AC_PATH_PROG(PATH_TO_SNMPGET,snmpget)
 AC_ARG_WITH(snmpget_command,
             ACX_HELP_STRING([--with-snmpget-command=PATH],