parse-gram: update the Bison interface

* src/parse-gram.y (%pure-parser, %name-prefix): Replace with...
(%define api.pure, %define api.prefix)
* src/location.h, src/scan-gram.h: Adjust to api.prefix.

src/parse-gram.y

@@ -94,14 +94,14 @@ current_lhs(symbol *sym, location loc, named_ref *ref)
 %}
 
 %debug
-%verbose
-%defines
-%locations
-%pure-parser
-%error-verbose
+%define api.prefix "gram_"
+%define api.pure
 %define parse.lac full
-%name-prefix="gram_"
+%defines
+%error-verbose
 %expect 0
+%locations
+%verbose
 
 %initial-action
 {