RFR(XS): 8213515: Improve freetype detection on linux/ppc64/ppc64le/s390x

[Volker Simonis]

Hi,

can I please have a review for the following trivial enhancement of
the freetype detection on linux/ppc64/ppc64le/s390x:

http://cr.openjdk.java.net/~simonis/webrevs/2018/8213515/
https://bugs.openjdk.java.net/browse/JDK-8213515

On some more "exotic" Linux platforms, libfreetype.so is found under
/usr/lib64/libfreetype.so even if the platform only supports 64-bits.
However, we currently only check for libfreetype.so under "/usr/lib"
and "/usr/lib/<ARCH>-linux-gnu". Another check under "/usr/lib64" does
no harm and greatly improves the usability on the mentioned platforms.

Thank you and best regards,
Volker