We don't use gthread anymore, remove leftovers.

Ubuntu doesn't (or didn't until recently?) ship icu pkg-config
files.  That's quite unfortunate.  Work around it.

Bug 57608 - ICU Detection fallback for non-pkgconfig systems

Newer automake / libtools warns otherwise.

As reported by Jonathan, OS X has setmode() that is something other
than what setmode() is on Win32.  So, limit invocation to Windows
platforms only.

Looks like Cygwin / MSVC declare it that way, and it still works on
MinGW32 cross.

Based on fontconfig patch from Raimund Steger.

Bug 55494 - ScriptItemizeOpenType doesn't exists under Windows XP

Instead of checking for ApplicationServices.h, which is present in all
versions of MacOSX, check for CTFontRef, a CoreText basic type.

https://github.com/grigorig/ucdn

Now that we have pthread detection in configure, we don't need Glib
anymore.  Glib will only be a Unicode data provider.

Import PortableFontInstance and add shaper stub.

Check for upstream-provided 'icu-uc' pkgconfig package.

A *real* release this time, with NEWS, ChangeLog, etc.

Apparently even that doesn't make check-internal-symbols.sh happy with
mingw32.  Going to disable that for DLLs again, but hopefully the
export-file is doing *something*.