Fixes #1081

Oops

* Handle EINTR on fallback reader
* Increase fallback reader limitation size limitation to 2 << 28
* Ensure _O_BINARY does exist if MMAP is used on Windows
  (maybe superfluous but makes me more confident)

Makes compiling without HAVE_ROUND on systems that do have it work.

Add one more "unlikely" annotation and use explicit nullptr check for more consistency.

And assign one bot to use the path always using NOMMAPFILEREADER token.

It's limited to 200mb so no more fun with using /dev/zero on hb-view!

In particular, if CoverageFormat2 has unsorted ranges, bail out.
Otherwise, 64k ranges of each 64k glyphs can DoS closure() method.

We can do the same for CoverageFormat1, but that one does not expose
the quadratic behavior, so, fine.

With this hb-view/hb-shape support pipes and possibly socket and named pipe
also, anything fails just on mmap.

We can later do the same for Windows also.

This however reveals two issues, the fact most of our bots don't have HAVE_MMAP and using
this instead the other fread/fopen reader can make failure on CI. I should look at them separately
this change however is very low risk I believe.

As https://github.com/harfbuzz/harfbuzz/pull/1059#issuecomment-397912812 we
like to still work with blobs that harfbuzz itself can't handle directly that are failing sanitization
currently apparently.

This checks if the blob isn't empty and uses `hb_face_count`
to see if the font file passes the simple font file sanitization
so can detect if the input is actually a font and checks also
whether input font-index is out of range.

We were passing the font path directly to freetype so rendering
was broken when we are getting the font from stdin.

This fixes it by using FT_New_Memory_Face instead.

This fixes:
* build/util/hb-view /dev/stdin text < font.ttf
* build/util/hb-view - text < font.ttf
* cat font.ttf | build/util/hb-view - text

but doesn't work on
* cat font.ttf | build/util/hb-view /dev/stdin text

which I will try to fix separately.

Fixes https://github.com/harfbuzz/harfbuzz/issues/864

Unfortunately 1.7.7 and 1.8.0 went out with the wrong hb-version.h contents.

Just include hb-static.cc in libharfbuzz-subset.so source list as
well.  Those building it built-in will include hb-static.cc once
already.  No need for any gymnastics.

Fixes #1054.

Following to https://ci.appveyor.com/project/harfbuzz/harfbuzz/build/1.0.1693/job/mfkjdhcdykjuqdfc

Followup to https://github.com/harfbuzz/harfbuzz/pull/1053

New API:
+hb_set_is_subset()