ibus: Point python interpreter to target location

it encoded PYTHON variable during build which otherwise points to python
on build host which is not correct for cross compiled packages.

Add missing dependency on python3-core which is needed for ibus-setup
script to run

Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-gnome/recipes-support/ibus/ibus.bb

@@ -38,4 +38,4 @@ FILES:${PN} += " \
 FILES:${PN}-dev += " \
     ${datadir}/gettext \
 "
-
+RDEPENDS:${PN} += "python3-core"

meta-gnome/recipes-support/ibus/ibus.inc

@@ -31,6 +31,9 @@ EXTRA_OECONF = " \
     --disable-emoji-dict \
     --disable-python2 \
 "
+EXTRA_OECONF:append:class-target = "\
+    --with-python=${bindir}/python3 \
+"
 
 do_configure:prepend() {
     touch ${S}/ChangeLog