python/pyicu: Add python3 support.

Signed-off-by: David Spencer <idlemoor@slackbuilds.org>

python/pyicu/README

@@ -1,2 +1,7 @@
 PyICU is a Python extension wrapping IBM's International
 Components for Unicode C++ library (ICU).
+
+python3 is an optional dependency.  You need to set PYTHON3=yes,
+for example:
+
+  PYTHON3=yes ./pyicu.SlackBuild

python/pyicu/pyicu.SlackBuild

@@ -59,6 +59,11 @@ find -L . \
 
 python setup.py install --root=$PKG
 
+if [ "${PYTHON3:-no}" = "yes" ]; then
+  rm -rf build
+  python3 setup.py install --root=$PKG
+fi
+
 find $PKG | xargs file | grep -e "executable" -e "shared object" | grep ELF \
   | cut -f 1 -d : | xargs strip --strip-unneeded 2> /dev/null || true