As MSVC doesn't implement C99, variable-length arrays
are not supported. We use _alloca instead.

Rationale: If memory allocation fails in the inner parse and we
longjump up the stack, the temporary arena will be missed and leak.

NB: This change means that any allocations done by the continuation
(in the form of new parsers, probably) will persist for the
lifetime of the parse result. Beware of wasting too much memory
this way! The bind continuation should generally keep dynamic
allocations to a minimum.

This BSD call will have to be implemented on windows. Right now
we have a stub that just exits the process.

NEWS:
* Switching endianness mid-byte no longer potentially re-reads bytes.
* bit_offset now consistently refers to the number of bits already
  read.
* HParsedTokens now have a bit_length field; this is a size_t.  This
  may be removed for memory reasons.

The bit writer has not yet been updated to match; the result of
switching bit writer endianness in the middle of a byte remains
undefined.

NetBSD's character class test macros are defined such that they produce
a compiler warning when given a char argument. Adding a cast to the call
fixes this.

Specify warning for internal only headers that are now installed for use
by extensions.

h_sequence need PB_MIN set.

Conflicts:
	src/bindings/python/SConscript
	src/bindings/python/hammer_tests.py

h_sequence need PB_MIN set.

Conflicts:
	src/bindings/python/SConscript
	src/bindings/python/hammer_tests.py

effects throughout, including use of inttypes.h/PRI[ud]64 because printf() is
still stuck in a long world, conversion of %lu to %zu for printing values of
type size_t, and changing/renaming the g_check_cmp* family of functions.