Replace another occurrence of strncpy with memcpy

* Replaced another line in jni_helper.c where
  the destination string that was copied by
  strncpy would contain a non-null terminated
  string.

Author: GauthamBanasandra

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/jni_helper.c

@@ -536,7 +536,7 @@ static ssize_t getClassPath_helper(const char *classpath, char* expandedClasspat
             // +1 for path separator or null terminator
             length += tokenlen + 1;
             if (expandedCP_curr != NULL) {
-                strncpy(expandedCP_curr, cp_token, tokenlen);
+                memcpy(expandedCP_curr, cp_token, tokenlen);
                 expandedCP_curr += tokenlen;
                 *expandedCP_curr = PATH_SEPARATOR;
                 expandedCP_curr++;