recipes: Start WORKDIR -> UNPACKDIR transition

Replace references of WORKDIR with UNPACKDIR where it makes sense to do
so in preparation for changing the default value of UNPACKDIR.

(From OE-Core rev: 1f18b9a512800860d5153d89eb82b56388efad6f)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/quilt/quilt.inc

@@ -67,7 +67,7 @@ DEPENDS:append:class-target = "${@bb.utils.contains('PTEST_ENABLED', '1', ' ptes
 PACKAGE_WRITE_DEPS += "ptest-runner"
 
 do_install_ptest() {
-	install ${WORKDIR}/test.sh ${D}${PTEST_PATH}
+	install ${UNPACKDIR}/test.sh ${D}${PTEST_PATH}
     mkdir ${D}${PTEST_PATH}/test
     install ${S}/test/* ${D}${PTEST_PATH}/test
     # mail needs a MTA, and the patch-wrapper is disabled