Have glr.cc pass (some of) the calc.at tests.

Have glr.cc pass (some of) the calc.at tests.
* data/glr.cc (b4_parse_param_orig): New.
(b4_parse_param): Improve its definition, and bound it more
clearly in the skeleton.
(b4_epilogue): Append, instead of prepending, in order to keep
#line consistency.
Simplify the generation of auxiliary functions: locations and
purity are mandated.
(b4_global_tokens_and_yystype): Honor it.
* data/location.cc (c++.m4): Don't include it.
* tests/local.at (_AT_BISON_OPTION_PUSHDEFS): Define AT_GLR_CC_IF
and AT_SKEL_CC_IF.
* tests/calc.at (AT_CHECK_CALC): Rely on AT_SKEL_CC_IF instead of
AT_LALR1_CC_IF.
Be sure to initialize the first position's filename.
(AT_CHECK_CALC_LALR1_CC): Add %location and %defines, they are
mandated anyway.
(AT_CHECK_CALC_GLR_CC): New.
Use it to exercise glr.cc as a lalr1.cc drop-in replacement.