parse: make grammar.y work with Bison 3

YYLEX_PARAM is no longer supported in Bison 3.

https://bugzilla.gnome.org/show_bug.cgi?id=706462
tests: remove silly test_fail_abstract_new check

Our check would make sure that GLib segfaults when
someone tries to instantiate an abstract type, which
is an extremely useful thing to check for.

In newer GLibs this is fixed and we get an abort with
a g_error() now it seems, so let's just remove this
check entirely.