lwtprint.c: don't use bare printf() for strings

- if somebody puts a "%" into the delimiter on the command line bad things happen.

src/lwtprint.c

@@ -502,7 +502,7 @@ int main( int argc, char **argv )
       for ( i=0; i<ncols; i++ ) {
 	icol = collist[i];
 	if ( i > 0 )
-          printf( delim );
+          printf( "%s", delim );
 	if ( icol == PSEUDOCOL_ROW )
 	  fprintf( stdout, "%d", irow );
 	else