udev: don't keep ptest testdata laying around

Only unpack udev's testdata right before executing the tests and cleanup
afterwards.

udev's testsuite can be used by ptest. However currently the testdata against
which its functionality is tested is installed in the sysroot at udev install
time.
If the sysroot is used with qemu the testdata makes qemu entering an infinite
loop.
http://lists.openembedded.org/pipermail/openembedded-core/2014-September/097098.html

This has already been fixed for the systemd udev flavour.
https://bugzilla.yoctoproject.org/show_bug.cgi?id=5664

(From OE-Core rev: 3f799b173d871160ab24666920f5e7ab4e09fd42)

Signed-off-by: Max Krummenacher <max.oss.09@gmail.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/udev/udev/add-install-ptest.patch

@@ -34,7 +34,7 @@ Upstream-Status: Pending
 +	(cd $(top_srcdir) && install $(TESTS) $(DESTDIR)/test)
 +	(cd $(top_srcdir) && install test/rule-syntax-check.py $(DESTDIR)/test)
 +	(cd $(top_srcdir) && install $(RULES) $(DESTDIR)/rules)
-+	tar -C $(DESTDIR)/test/ -xJf $(top_srcdir)/test/sys.tar.xz
++	cp $(top_srcdir)/test/sys.tar.xz $(DESTDIR)/test/
 --- a/test/udev-test.pl	2012-03-18 16:43:36.000000000 +0100
 +++ b/test/udev-test.pl	2013-02-18 10:31:29.706357321 +0100
 @@ -1459,11 +1459,13 @@

meta/recipes-core/udev/udev/run-ptest

@@ -1,3 +1,5 @@
 #!/bin/sh
 
+tar -C test/ -xJf test/sys.tar.xz
 make -k check-TESTS
+make test-sys-distclean