opkg: fix ptest packaging when OPKGLIBDIR == libdir

opkg: fix ptest packaging when OPKGLIBDIR == libdir

there is small issue with ptest packaging in cases where
OPKGLIBDIR is set to /usr/lib.

Then all ptest files get packaged in libopkg instead of opkg-ptest and correct QA error is triggered:
ERROR: QA Issue: /usr/lib/opkg/ptest/tests/opkgcl.py contained in package libopkg requires /usr/bin/python3, but no providers found in RDEPENDS_libopkg? [file-rdeps]

  # $FILES_libopkg
  #   set /jenkins/mjansa/build-webos-master/oe-core/meta/recipes-devtools/opkg/opkg_0.4.0.bb:62
  #     "${libdir}/*.so.* ${OPKGLIBDIR}/opkg/"
  FILES_libopkg="/usr/lib/*.so.* /usr/lib/opkg/"

  # $FILES_opkg-ptest [2 operations]
  #   set /jenkins/mjansa/build-webos-master/oe-core/meta/classes/ptest.bbclass:9
  #     "${PTEST_PATH}"
  #   rename from FILES_${PN}-ptest data.py:117 [expandKeys]
  #     "${PTEST_PATH}"
  # pre-expansion value:
  #   "${PTEST_PATH}"
  FILES_opkg-ptest="/usr/lib/opkg/ptest"

  # $PACKAGES [4 operations]
  #   set /jenkins/mjansa/build-webos-master/oe-core/meta/conf/bitbake.conf:292
  #     "${PN}-src ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}"
  #   set /jenkins/mjansa/build-webos-master/oe-core/meta/conf/documentation.conf:314
  #     [doc] "The list of packages to be created from the recipe."
  #   prepend /jenkins/mjansa/build-webos-master/oe-core/meta/classes/ptest.bbclass:20
  #     "${@bb.utils.contains('PTEST_ENABLED', '1', '${PN}-ptest', '', d)}"
  #   prepend /jenkins/mjansa/build-webos-master/oe-core/meta/recipes-devtools/opkg/opkg_0.4.0.bb:60
  #     "libopkg"
  # pre-expansion value:
  #   "libopkg ${@bb.utils.contains('PTEST_ENABLED', '1', '${PN}-ptest', '', d)} ${PN}-src ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}"
  PACKAGES="libopkg opkg-ptest opkg-src opkg-dbg opkg-staticdev opkg-dev opkg-doc opkg-locale  opkg"

The easiest fix should be to reorder PACKAGES (the _prepends) so that ${PN}-ptest is prepended later -> ends before libopkg).

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>