Prevent resource leak

If -f was used as an argument twice to the program, then it would leak
the file resource, due to overwriting it on the second pass

Signed-off-by: Paul Elliott <paul.elliott@arm.com>

programs/ssl/ssl_context_info.c

@@ -222,6 +222,12 @@ void parse_arguments( int argc, char *argv[] )
                 error_exit();
             }
 
+            if( NULL != b64_file )
+            {
+                printf_err( "Cannot specify more than one file with -f\n" );
+                error_exit( );
+            }
+
             if( ( b64_file = fopen( argv[i], "r" )) == NULL )
             {
                 printf_err( "Cannot find file \"%s\"\n", argv[i] );