RFR: 8250894 : Provide a configure option to build and run against the platform libharfbuzz

[Philip Race]

bug: https://bugs.openjdk.java.net/browse/JDK-8250894
webrev : http://cr.openjdk.java.net/~prr/8250894/

Since https://bugs.openjdk.java.net/browse/JDK-8249821 has now separated
out libharfbuzz from libfontmanager, it would be natural for distros
to want to link against the libharfbuzz that they distribute with the
platform, as is done for libfreetype. But there is no way to do it.

This fix adds a --with-harfbuzz=system configure option.
The valid values are system and bundled.
If specifying system it checks to see if you have the harfbuzz 
development package installed

Like similar options it is only useful on platforms that distribute
libharfbuzz, so there is no need to try to support windows and macOS for 
this option
and it will fast fail at configure time on those platforms.

I have verified this fix on Ubuntu 20.04 LTS.

-phil.