Don't know why I thought I should subtract one there...

llvm-gcc-4.2 bot had this problem:
hb-private.hh:812: error: initializer specified for non-virtual method 'void hb_vector_t<Type, StaticSize>::operator=(const hb_vector_t<Type, StaticSize>&) [with Type = hb_user_data_array_t::hb_user_data_item_t, unsigned int StaticSize = 1u]'

Removing the delete didn't work with a constructor. So, remove constructor.
Just disallow assignment.  Still better than nothing.

Clang build was failing with:

/usr/bin/ld: .libs/libharfbuzz_la-hb-blob.o: relocation R_X86_64_PC32 against undefined hidden symbol `_ZTH12_hb_CrapPool' can not be used when making a shared object

Instead of fighting it, just disable use of it.

This reverts commit face7cf5.

This reverts commit 7bf19801.

Fully untested.

MAP_NORESERVE is not available on macOS for example so set the flag
to zero if not defined on the headers.

If a pointer type was passed to Null(), reinterpret_cast<> was
complaining about qualifiers being removed. Turns out I need the const on
the other side of "Type" to fix that.  Also remove unused const from
NullPool type.

Not sure if I like to keep it. For now, aim for correctness.

Common Regoin for Access Protection.  Like the NullPool, but writable.

Makes for cleaner code.

Fixup for previous commit. Was accidentally turned off.

Make clang happy. Also, don't use anonymous union.

We'll see if this sticks to the bots.

"writable" is not in use and probably we can go in the reverse direction
and remove the flags that are useful for enabled writable, this is just
for the sake of completeness however.

It removes io.h and other polyfills which we no longer need as 7e76d746

This makes it compatible with ARMCC which I had access in
a collaboration with @imgtec, thanks!

Basically hb_blob_create_from_file features three code paths,
mmap, Win32 and fallback.

We had fallback implementation even before this but it was relied
to "open" which is not available on some environments. This change
improved the situtation by using only fopen and friends for
fallback path.

Interestingly we could use "open" on Windows but in fact it was
emulated by MSVCRT so I've completely split that from Unix path
now that we have a distinct path for fallback path also.