clang++ does not allow struct definitions inside a type specifier,
offsetof() in datatypes.h
Thus probe for clang++ only for all ALIGNOF values in a
new auto::alignof step. This is normally skipped. Add the
definitions to feature.h.
clang++ prints always a warning on c sources.
Move -x c++ from warnings upfront to cc, probed in auto::gcc
to be able to correctly probe for warnings and attributes.
This fixed almost all clang++ warnings, only dynoplibs
-Wno-parentheses-equality is missing for those.
Before we hardcoded clang++ as only compiler which does not compile
struct definitions inside a type specifier, offsetof() in datatypes.h.
Probe now for this behavior, and set HAS_COMPILER_OFFSETOF_ALIGNOF.
1 if allowed at compile-time, and undef if not and various
PARROT_ALIGN_<type> definitions are precomputed.
Also fix parrot/datatypes.h codingstd.
Currently we have "yes"/"no", sometimes "done", "skipped" and some
steps report more. Library checks report "no" or "yes, version".
This improve at least the library steps, which can be omitted
with --without-lib to print "skipped" instead of "no".
no could mean not requested or not found.
"not requested" (llvm) is harmonized to "skipped".
"done" is for steps with no other results than done.