* data/yacc.c (YY_LOCATION_PRINT): Use YYLTYPE_IS_TRIVIAL as a

clearer criterion to define it.
(parse): Initialize the initial location when YYLTYPE_IS_TRIVIAL.
When reducing on an empty RHS, use the latest stacked location as
location.
yylloc is not always available.
* data/glr.c: Likewise.
Also, honor initial-actions.