package/harfbuzz: add introspection support

package/harfbuzz: add introspection support

Add introspection support to harfbuzz otherwise activation of
introspection in pango 1.46.1 will fail on:

Couldn't find include 'HarfBuzz-0.0.gir' (search path: '['/home/naourr/work/instance-2/output-1/host/aarch64-buildroot-linux-gnu/sysroot/usr/bin/../share/gir-1.0', '/home/naourr/work/instance-2/output-1/host/share/gir-1.0', '/home/naourr/work/instance-2/output-1/host/share', '/home/naourr/.local/share/flatpak/exports/share/gir-1.0', '/var/lib/flatpak/exports/share/gir-1.0', '/usr/local/share/gir-1.0', '/usr/share/gir-1.0', '/home/naourr/work/instance-2/output-1/host/share/gir-1.0', '/usr/share/gir-1.0']')

Fixes:
 - http://autobuild.buildroot.org/results/3357225ee2d8392bfd57af91cde04a1113e03493

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>