Check net-snmp-config's existence in case user specified the
ac_cv_prog_NETSNMP to avoid HAVE_SNMP defined if the specified
net-snmp-config doesn't exist.

Upstream-Status: Inappropriate [Embedded specific]

Signed-off-by: Yao Zhao <yao.zhao@windriver.com>
---
diff --git a/configure.in b/configure.in
index 6f3e88f..8ddf017 100755
--- a/configure.in
+++ b/configure.in
@@ -1423,7 +1423,7 @@ dnl> NET-SNMP
 dnl>
 if test ".${ac_disable_snmp}" != ".yes"; then
   AC_CHECK_TOOL(NETSNMP, net-snmp-config)
-  if test -n "$NETSNMP"; then
+  if test -n "$NETSNMP" -a -e "$NETSNMP"; then
     AC_DEFINE_UNQUOTED(HAVE_SNMP, 1, [SNMP is supported])
     SNMPLIBS="`$NETSNMP --libs`"
     SNMPLIBS="`echo ${SNMPLIBS}|sed -e s,'-R../lib',,g`"