Create tests/local.at for Bison generic testing macros.
* tests/calc.at (AT_CHECK_PUSHDEFS, AT_CHECK_POPDEFS): Move to...
* tests/local.at (AT_BISON_OPTION_PUSHDEFS, AT_BISON_OPTION_POPDEFS):
This new file.
* tests/calc.at (AT_CHECK_CALC): Adjust.
* tests/testsuite.at (AT_DATA_GRAMMAR_PROLOGUE, AT_DATA_GRAMMAR)
(AT_COMPILE, AT_COMPILE_CXX, AT_PARSER_CHECK): Move to...
* tests/local.at: here.
(AT_COMPILE_CXX): Tags the tests using it as c++.
Ignore the test if CXX is not functional.